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1
Venugopal, S. "Study On Overmodulation Methods For PWM Inverter Fed AC Drives." Thesis, Indian Institute of Science, 2006. https://etd.iisc.ac.in/handle/2005/278.
Full textAbstract:
A voltage source inverter is commonly used to supply a variable frequency variable voltage to a three phase induction motor in a variable speed application. A suitable pulse width modulation (PWM) technique is employed to obtain the required output voltage in the line side of the inverter. Real-time methods for PWM generation can be broadly classified into triangle comparison based PWM (TCPWM) and space vector based PWM (SVPWM).
In TCPWM methods such as sine-triangle PWM, three phase reference modulating signals are compared against a common triangular carrier to generate the PWM signals for the three phases.
In SVPWM methods, a revolving reference voltage vector is provided as voltage reference instead of three phase modulating waves. The magnitude and frequency of the fundamental component in the line side are controlled by the magnitude and frequency, respectively, of the reference vector.
The fundamental line side voltage is proportional to the reference magnitude during linear modulation. With sine-triangle PWM, the highest possible peak phase fundamental voltage is 0.5Vdc, where Vdc is the DC bus voltage, in the linear modulation zone. With techniques such as third harmonic injection PWM and space vector based PWM, the peak phase fundamental voltage can be as high as (formula) (i.e., 0:577Vdc)during linear modulation. To increase the line side voltage further, the operation of the VSI must be extended into the overmodulation region. The overmodulation region extends upto the six-step mode, which gives the highest possible ac voltage for a given (formula).
In TCPWM based methods, increasing the reference magnitude beyond a certain level leads to pulse dropping, and gradually leads to six-step operation. However, in SVPWM methods, an overmodulation algorithm is required for controlling the line-side voltage during overmodulation and to achieve a smooth transition from PWM to six-step mode.
Numerous overmodulation algorithms have been proposed in the literature for space vector modulated inverter. A well known algorithm among these divides the overmodulation zone into two zones, namely zone-I and zone-II. This is termed as the 'existing overmodulation algorithm' here. This algorithm is modified in the present work to reduce computational burden without much increase in the line current distortion.
During overmodulation, the fundamental line side voltage and the reference magnitude are not proportional, which is undesirable from the control point of view. The present work ensures a linear relationship between the two.
Apart from the fundamental component, the inverter output voltage mainly consists of harmonic components at high frequencies (around switching frequency and the integral multiples) during linear modulation. However, during overmodulation, low order harmonic components such as 5th, 7th, 11th, 13th etc., are also present in the output voltage. These low order harmonic voltages lead to low order harmonic currents in the motor. The sum of the lower order harmonic currents is termed as 'lower order current ripple'. The present thesis proposes a method for estimation of lower order current ripple in real-time.
In closed loop current control, the motor current is fed back to the current controller. During overmodulation, the motor current contains low order harmonics, which appear in the current error fed to the controller. These harmonic currents are amplified by the current error amplifier deteriorating the performance of the drive.
It is possible to filter the lower order harmonic currents before being fed back. However, filtering introduces delay in the current loop, and reduces the bandwidth even during linear modulation. In the present work, the estimated lower order current ripple is subtracted from the measured current before the latter is fed back to the controller.
The estimation of lower order current ripple and the proposed current control are verified through simulation using MATLAB/SIMULINK and also experimentally on a laboratory prototype. The experimental setup comprises of a field programmable gate arrays (FPGA) based digital controller, an IGBT based inverter and a four-pole squirrel cage induction motor.
(Pl refer the original document for formula)
2
Venugopal, S. "Study On Overmodulation Methods For PWM Inverter Fed AC Drives." Thesis, Indian Institute of Science, 2006. http://hdl.handle.net/2005/278.
Full textAbstract:
A voltage source inverter is commonly used to supply a variable frequency variable voltage to a three phase induction motor in a variable speed application. A suitable pulse width modulation (PWM) technique is employed to obtain the required output voltage in the line side of the inverter. Real-time methods for PWM generation can be broadly classified into triangle comparison based PWM (TCPWM) and space vector based PWM (SVPWM).
In TCPWM methods such as sine-triangle PWM, three phase reference modulating signals are compared against a common triangular carrier to generate the PWM signals for the three phases.
In SVPWM methods, a revolving reference voltage vector is provided as voltage reference instead of three phase modulating waves. The magnitude and frequency of the fundamental component in the line side are controlled by the magnitude and frequency, respectively, of the reference vector.
The fundamental line side voltage is proportional to the reference magnitude during linear modulation. With sine-triangle PWM, the highest possible peak phase fundamental voltage is 0.5Vdc, where Vdc is the DC bus voltage, in the linear modulation zone. With techniques such as third harmonic injection PWM and space vector based PWM, the peak phase fundamental voltage can be as high as (formula) (i.e., 0:577Vdc)during linear modulation. To increase the line side voltage further, the operation of the VSI must be extended into the overmodulation region. The overmodulation region extends upto the six-step mode, which gives the highest possible ac voltage for a given (formula).
In TCPWM based methods, increasing the reference magnitude beyond a certain level leads to pulse dropping, and gradually leads to six-step operation. However, in SVPWM methods, an overmodulation algorithm is required for controlling the line-side voltage during overmodulation and to achieve a smooth transition from PWM to six-step mode.
Numerous overmodulation algorithms have been proposed in the literature for space vector modulated inverter. A well known algorithm among these divides the overmodulation zone into two zones, namely zone-I and zone-II. This is termed as the 'existing overmodulation algorithm' here. This algorithm is modified in the present work to reduce computational burden without much increase in the line current distortion.
During overmodulation, the fundamental line side voltage and the reference magnitude are not proportional, which is undesirable from the control point of view. The present work ensures a linear relationship between the two.
Apart from the fundamental component, the inverter output voltage mainly consists of harmonic components at high frequencies (around switching frequency and the integral multiples) during linear modulation. However, during overmodulation, low order harmonic components such as 5th, 7th, 11th, 13th etc., are also present in the output voltage. These low order harmonic voltages lead to low order harmonic currents in the motor. The sum of the lower order harmonic currents is termed as 'lower order current ripple'. The present thesis proposes a method for estimation of lower order current ripple in real-time.
In closed loop current control, the motor current is fed back to the current controller. During overmodulation, the motor current contains low order harmonics, which appear in the current error fed to the controller. These harmonic currents are amplified by the current error amplifier deteriorating the performance of the drive.
It is possible to filter the lower order harmonic currents before being fed back. However, filtering introduces delay in the current loop, and reduces the bandwidth even during linear modulation. In the present work, the estimated lower order current ripple is subtracted from the measured current before the latter is fed back to the controller.
The estimation of lower order current ripple and the proposed current control are verified through simulation using MATLAB/SIMULINK and also experimentally on a laboratory prototype. The experimental setup comprises of a field programmable gate arrays (FPGA) based digital controller, an IGBT based inverter and a four-pole squirrel cage induction motor.
(Pl refer the original document for formula)
3
Satiawan, I. Nyoman Wahyu. "Pulse width modulation control of dual-inverter supply for five-phase variable-speed drives." Thesis, Liverpool John Moores University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.585478.
Full textAbstract:
Three-phase multi-level topologies have been drawing increased attention in the past two decades. The numerous advantages of multi-level supply include: good power quality (low voltage distortion and dv/dt), good electromagnetic compatibility, operation with a lower switching frequency (lower switching losses), high voltage capability, smaller common mode (CM) voltage (reducing the stress in the motor bearings). There are various topologies of multilevel converters. The main ones are the neutral point clamped (NPC), the flying capacitor (FC) and the cascaded converters. Another alternative is the dual two-level inverter configuration supplying an open-end winding machine. This topology has received growing attention due to its simple structure. The open-end topology has the advantages that the additional diodes used in the neutral- point-clamped (NPC) voltage source inverter (VSI) are not needed, leading to a saving in the overall number of components. Furthermore, the issue of proper capacitor voltage balancing does not exist if the supply is two-level at each winding side. Application of such a dual-inverter supply (with equal DC-links) enables drive operation with voltage waveform equivalent to the one obtainable with a three-level VSI. The advantages of multi-phase variable speed drives over the three-phase ones are numerous and include an increase of fault tolerance, the possibility to have several multi-phase machines connected in series and drive them independently with a single VSI and, when the machine is equipped with a concentrated winding, other, higher harmonics can also be used to increase the developed torque. This thesis explores the possibility of combining the multi-phase and open-end- winding multi-level topologies. In particular the five-phase open-end-winding topology is considered. General properties of the five-phase AC motor drives with sinusoidal winding distribution are at first reviewed, along with the previously developed two- level space-vector modulation algorithm for a five-phase two-level VSI. A mathematical model of the converter is developed and a detailed study of the available switching states and corresponding voltage space vectors is conducted. It is shown that, due to the large number of switching states available in the topology together with the additional requirements when driving a multi-phase machine, the design of a suitable modulation scheme is extremely challenging. Three different space-vector modulation methods are proposed in the thesis. The developed methods are relatively simple to implement since they consider each inverter individually hence breaking down the problem into one of simpler complexity. The three modulation methods and the performance of the five- phase drive are verified using simulations. Finally, a laboratory prototype is described, which utilises two two-level five- phase inverters connected across an open-end-winding five-phase induction machine. The three modulation schemes are implemented using a fast prototyping control system (dSP ACE) and the performance of the modulation techniques is compared. The motor is controlled in V/fmode, in open loop. It is demonstrated that two of the methods produce multi-level output waveforms and that one method offers superior performance, with reduced converter losses.
4
Patkar, Fazlli. "PWM techniques for control of dual-inverter supplied six-phase drives." Thesis, Liverpool John Moores University, 2013. http://researchonline.ljmu.ac.uk/4463/.
Full textAbstract:
Among the different multiphase ac drive solutions, one of the most widely reported in the literature is the six-phase machine. The machines can be realised into two different configurations, symmetrical and asymmetrical. For the symmetrical configuration, the stator winding consists of two sets of three-phase windings that are spatially shifted by 60 degrees where spatial displacement between any two consecutive phases is the same and equal to 60 degrees. For the asymmetrical configuration, the two sets of three-phase windings are spatially shifted by 30 degrees. As a result, the spatial shift between consecutive phases becomes non-equidistant. In this thesis, modulation techniques for both symmetrical and asymmetrical six-phase machines are investigated. The machines are configured in open-end winding configuration where both ends of the stator winding are connected to separate isolated inverters in a topology known as dual-inverter supply. Compared to conventional single-sided supply topology where one end of the winding is connected to an inverter while the other side is star-connected, some additional benefits are offered by the dual-inverter supply topology. First, fault tolerance of the drive is improved, since the supply is realised with two independent inverters. In case one of the inverters is faulted, the other can continue to provide power to the machine. Second, the same phase voltages can be achieved with half the dc-link voltages on the two inverter inputs compared to the single-sided supply, which can be useful in applications such as electric and hybrid electric vehicles and medium sized ships, where the dc voltage levels are limited. Further, due to the nature of the topology, additional diodes and capacitors like in the Neutral Point Clamped (NPC) and Flying Capacitor (FC) VSIs are not required. The latter results in a further advantage - capacitor voltage balancing techniques are not required. Two pulse width modulation (PWM) techniques for control of the dual-inverter supplied six-phase drives are proposed in this thesis. The first is a reference sharing algorithm where the inverters are modulated using reference voltage that is shared equally and unequally between the two modulators. For both symmetrical and asymmetrical six-phase drives, a better performance, in term of total harmonic distortion (THD) of phase voltage is obtained when the reference is shared unequally between the two modulators. The second technique is carrier-based modulation where the modulation of the two inverters is determined by the disposition of the carrier signals. Three variations of carrier signals disposition are investigated namely; the phase disposition (PD-PWM), alternate phase opposition disposition (APOD-PWM) and phase-shifted PWM (PS-PWM). For the symmetrical six-phase drive, the best phase voltage and current THDs are obtained using APOD-PWM while for asymmetrical six-phase drive, the APOD-PWM produces the worst current THD despite having the best voltage THD among the three methods. All the developed modulation techniques are analysed using simulations and experiments undertaken using a laboratory prototypes. The waveforms and spectra of phase voltage and load current obtained from the simulation and experimental works are presented in this thesis together with the THD of both the voltage and current over entire linear modulation range.
5
Nusair, Ibrahim Rakad. "Comparison Between PWM and SVPWM Three-Phase Inverters in Industrial Applications." Youngstown State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1355949821.
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Krohn, Austin Bengoechea. "Electro-Thermal Dynamics and the Effects of Generalized Discontinuous Pulse Width Modulation Algorithms on High Performance Variable Frequency Drives." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397643253.
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Afiat, Milani Alireza. "Voltage regulation in a single-stage three-phase boost-inverter using modified phasor pulse width modulation method for stand-alone applications." Thesis, Kansas State University, 2013. http://hdl.handle.net/2097/16219.
Full textAbstract:
Master of Science<br>Department of Electrical and Computer Engineering<br>Behrooz Mirafzal<br>In this thesis, a modified version of the phasor pulse width modulation (PPWM) switching method for use in a single-stage three-phase boost inverter is presented. Because of the required narrow pulses in the PPWM method and limitations in controller resolution, e.g. dSPACE, the desired switching pattern for a boost inverter requires a costly processor. A low resolution processor can cause pulse dropping which results in some asymmetric conditions in output waveforms of the boost inverter and therefore, an increase in the THD of the output waveform. In order to solve this problem, a new switching pattern is developed which guarantees symmetric conditions in the switching pattern by discretizing the switching pattern in every switching cycle. This switching pattern has been applied to a boost inverter model developed by SimPowerSystems toolbox of MATLAB/Simulink. The model has been simulated in a wide range of input DC voltage and load. Moreover, a laboratory-scaled three-phase boost inverter has been designed, built, and tested using an identical switching pattern in the same input voltage
and load range. Both simulation and experimental results confirm the effectiveness of the new switching pattern.
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Tolbert, Leon M. "New multilevel carrier-based pulse width modulation techniques applied to a diode-clamped converter for use as a universal power conditioner." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/14992.
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ANDRADE, Felipe Corrêa de. "Modulação Escalar Generalizada para Redução de Perdas em Conversores Nove Chaves." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/18040.
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Previous issue date: 2015-07-31<br>Capes<br>O conversor nove chaves (Nine-Switch Inverter - NSI) foi proposto recentemente e, desde então,
um grande número de aplicações foi explorado para esta nova topologia, especialmente como
um possível substituto do tradicional conversor back-to-back. A principal vantagem do NSI
é o menor número de chaves (nove em vez de doze do conversor back-to-back), que, como
consequência, acarreta em restrições nas amplitudes de saída do inversor. Na literatura, foram
propostas diferentes técnicas de modulação por largura de pulso (Pulse Width Modulation -
PWM) que respeitam estas restrições. Diante deste cenário, o presente trabalho propõe duas
abordagens para a generalização da modulação no NSI: a modulação escalar quasi generalizada
e a generalizada, que são baseadas no conceito de generalização para o inversor trifásico fonte
de tensão (VSI) convencional e que podem ser facilmente implementadas com um reduzido
esforço computacional. Este conceito propicia, através de uma abordagem sistemática e direta,
a geração de qualquer técnica de PWM, seja ela contínua ou descontínua, através do ajuste de
graus de liberdade específicos. Objetivando a redução de perdas, são apresentados os graus de
liberdade específicos que, quando aplicados nas modulações propostas, aumentam o rendimento
do inversor. Resultados de simulação confirmam a funcionalidade das modulações.<br>The nine-switch inverter (NSI) has been proposed recently and, since then, a large number
of applications were explored for this new topology, specially as a possible substitute to the
traditional back-to-back converter. The main advantage of the NSI is its lesser number of
switches (nine instead of twelve of the back-to-back converter), which, as a consequence, leads
to some restrictions in the total attainable amplitude at its outputs. In literature, many pulse width
modulation (PWM) techniques were proposed respecting those restrictions. In this scenario,
this paper proposes two generalization approaches for the modulation of the NSI: the quasi
generalized scalar modulation and the generalized scalar modulation, which are based on the
generalization concept for the voltage source inverter (VSI), easily implemented with a reduced
computational effort. Such concept leads to a systematic and straight approach to the generation
of any continuous or discontinuous PWM technique for the NSI, simply adjusting a few degrees
of freedom of the modulation strategy. Aiming the reduction of the power losses, specific degrees
of freedom are presented, for the proposed modulations. Simulation results confirm the validity
of the proposed methods.
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Paterakis, Fotis Konstantinos. "Development of alternative pulse width modulation methods for conventional and multilevel voltage source inverters." Thesis, Brunel University, 2016. http://bura.brunel.ac.uk/handle/2438/13856.
Full textAbstract:
Multilevel inverters have attracted wide interest in both the academic community and the industry for the past decades. Therefore, the investigation and development of modulation strategies in multilevel inverters emerges as a necessity for the industry and researchers. In this doctoral thesis, alternative modulation methods suitable for three-level conventional single-phase inverters and especially for cascade H-bridge multilevel inverters are discussed and proposed. The theory of Equal Areas is reformed and presented and its modifications are proposed. These modifications are compared with other well-known modulation schemes, such as carrier-based modulation schemes and programmed pulse width modulation techniques. The advantage of the modified Equal Areas Pulse Width Modulation (EAPWM) is its algorithmic simplicity due to simple algebraic relationships, which results in less computational effort. A fully mathematical formulation for the Equal Areas modulation is proposed for both conventional and multilevel inverters. The EAPWM is shown to produce well-formed switched output voltages that have low total harmonic distortion at even low switching frequencies. The importance of this thesis is complimented by the results, produced after the implementation of EAPWM in multilevel inverters, which can be used as a more accurate reference when compared with other modulation strategies. Moreover, this direct modulation strategy has been extended to work on higher amplitude modulation ratios, in a linear manner, while entering the over modulation region. In this context, modified algorithms have been developed using different criteria for the calculation of the pulses’ width and their placement inside the time interval. The equal areas method, implemented in conventional single-phase inverters, uses odd pulse numbers per half cycle, holding integer frequency ratios in contrast to its implementation in multilevel inverters, where non-integer frequency ratios occur due to the level-by-level application. The application of the method is verified by simulations together with experimental work using a full-scale prototype inverter.
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Marwali, Mohammad Nanda Rahmana. "Digital control of pulse width modulated inverters for high performance uninterruptible power supplies." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1100484647.
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Thesis (Ph. D.)--Ohio State University, 2004.<br>Title from first page of PDF file. Document formatted into pages; contains xviii, 224 p.; also includes graphics. Includes bibliographical references (p. 199-211).
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Cetin, Nebi Onur. "Design And Implementation Of Advanced Pulse Width Modulation Techniques And Passive Filters For Voltage Source Inverter Driven Three-phase Ac Motors." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612236/index.pdf.
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Advanced pulse width modulation (PWM) techniques such as space vector PWM, active zero state PWM, discontinuous PWM, and near state PWM methods are used in three-phase AC motor drives for the purpose of obtaining low PWM current ripple, wide voltage linearity range, and reduced common mode voltage (CMV). In some applications, a filter is inserted between the inverter and the motor for the purpose of reducing the stresses in the motor. The motor current PWM ripple components, terminal voltage overshoots, shaft voltage, and bearing currents, etc. can all be reduced by means of PWM techniques and passive filters. Various PWM techniques and passive filter types exist. This thesis studies the combinations of PWM techniques and filters and evaluates the performance of the motor drive in terms of the discussed stresses in the motor. PWM techniques are reviewed, a generalized algorithm for the implementation of PWM techniques is developed, and implementation on a 4 kW rated drive is demonstrated. Filter types are studied, among them the common mode inductor and the pure sine filter (PSF) configurations are investigated in detail. Filters are designed and their laboratory performance is evaluated. In the final stage the advanced PWM techniques and filters are combined, the incompatibility problem of discontinuous PWM methods with the PSF is illustrated. A cure based on rate of change limiter is proposed and its feasibility proven in the laboratory experiments. With the use of the proposed PWM algorithm and PSF, a motor drive with ideal DC to AC conversion stage (DC to pure sine) is achieved and its performance is demonstrated in the laboratory.
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Dujic, Dražen. "Development of pulse-width-modulation techniques for multi-phase and multi-leg voltage source inverters." Thesis, Liverpool John Moores University, 2008. http://researchonline.ljmu.ac.uk/5897/.
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A huge body of work has been published in recent times in the area of multi-phase machines and drives. Many aspects of these drives have been analysed, such as reduction of torque pulsations, increased reliability and fault tolerance, improved power sharing capabilities and possibilities for realisation of series-connected multi-motor drives with supply coming from a single multi-phase voltage source inverter (VSI). Various pulse width modulation (PWM) schemes have been developed for multi-phase machines with concentrated and distributed windings, utilising both carrier-based PWM and space vector PWM (SVPWM) approaches. However, no systematic analysis has been performed in order to determine properties of multi-phase PWM in general, and to establish close correlation between carrier-based PWM and space vertor PWM, for multi-phase VSIs. This thesis presents an analysis and development of multi-phase PWM schemes for sinusoidal output voltage generation with two-level muhi-phase VSIs, which are suitable for multi-phase machines with distributed windings. Therefore, attention is paid to the elimination of low order harmonics. The scope of the thesis has been narrowed down to the continuous PWM schemes and operation in the linear region of the modulation only. Both multi-phase carrier-based PWM and SVPWM schemes are considered, and, in particular, five-phase, seven-phase e-phase systems are addressed in detail. Thus, a strong link between these two different approaches is established, allowing for an easier comparison of the features offered by each method. All PWM schemes are practically implemented in a DSP and experimentally verified through extensive experimentation on the custom-built multi-phase VSI. In addition to the methods of sinusoidal output voltage generation, achieved by means of the synthesis of the reference in only the first plane of the multi-phase system with simultaneous zeroing of voltages in all the other planes.
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Pothuraju, Maneesha. "A Study on the Electromagnetic and Mechanical Vibrations of a Dynamometer Using Spectral Analysis." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613747909641685.
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Olsson, Johanna. "Implementation of Nodes in HVDC Grids." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293884.
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This project is made for a deeper understanding ofhow frequency and amplitude of the waves that create the controlwave in a Pulse Width Modulated 2-level inverter affect the powerquality and power losses. The results were that a high frequencyreduces the Total Harmonic Distortion but increases the powerloss. The amplitude, however, reduces both the Total HarmonicDistortion and the power loss as it increases. All the analyseswere done in a simulation program called Simulink. The resultscan be applied when improving High Voltage Direct Currentinverters to develop a functional High Voltage Direct Currentgrid that enables wider use of renewable energy sources.<br>Projektet syftar till att få en djupare förståelse för hur frekvensen och amplituden på de vågor som skapar kontollvågen i en pulsbreddsmodulerad likspänningsomvandlare med två nivåer påverkar effektkvalitén och effektförlusterna. Resultatet av studien var att en hög frekvens minskar ”Total Harmonic Distortion” men ökar effektförlusterna. Amplituden å andra sidan reducerar både ”Total Harmonic Distortion” och effektförlusterna när den ökar. Alla analyserna är gjorda i simuleringsprogrammet Simulink. Resultaten kan appliceras när högspända likspänningsomvandlare vidareutvecklas för att skapa ett fungerande högspänt-likströms elnät som öppnar upp för en bredare användning av förnyelsebara energikällor.<br>Kandidatexjobb i elektroteknik 2020, KTH, Stockholm
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Espindola, Marcos Fernando. "Estudo e implementação de inversor de tensão a três níveis com modulação em largura de pulsos por vetores espaciais aplicado ao controle vetorial de motor síncrono de imãs permanentes = Study and implementation of three level voltage inverter with space vector modulation by pulse width modulation applied to vector control of permanent magnet synchronous motor." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/259011.
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Orientadores: Ernesto Ruppert Filho, Marcelo Gradella Villalva<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação<br>Made available in DSpace on 2018-08-21T14:53:53Z (GMT). No. of bitstreams: 1
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Previous issue date: 2012<br>Resumo: Apresenta-se a implementação de um inversor trifásico de tensão a três níveis para ser utilizado no controle de velocidade de um motor síncrono trifásico a imãs permanentes usando o método de controle vetorial. Realizou-se o estudo, projeto e construção de um inversor de tensão a três níveis com neutro grampeado ou inversor NPC neutral point clamped. Utilizou-se modulação em largura de pulsos por vetores espaciais no controle vetorial de velocidade do motor. Foram realizadas simulações do sistema proposto usando os aplicativos computacionais Matlab/Simulink e PSIM. Realizou-se em seguida uma montagem experimental constituída de um motor síncrono a imãs permanentes de 0,75 kW acoplado a um freio eletromagnético que lhe serviu de carga mecânica. O sistema motor e carga foi acionado pelo inversor com modulação em largura de pulsos por vetores espaciais e os resultados obtidos do controle de velocidade realizado, incluindo reversão de velocidade e frenação do motor, são apresentados no trabalho. Comparou-se também o desempenho de um inversor a três níveis usando modulação em largura de pulsos por vetores espaciais com o desempenho de um inversor a dois níveis usando modulação em largura de pulsos por vetores espaciais na alimentação de uma carga resistiva. Resultados de simulação e resultados experimentais são apresentados. Neste trabalho realizou-se uma comparação qualitativa entre o uso do inversor a dois níveis e do inversor a três níveis que mostra em que situações é conveniente utilizar o inversor a três níveis<br>Abstract: It is presented the implementation of a three phase three level voltage inverter to be used in the speed control of a three phase permanent magnet synchronous motor using the vector control method. To achieve this goal, it was carried out the study, design and construction of a three level neutral point clamped voltage inverter or NPC inverter. For the control of the motor it was used a space vector modulation. The proposed system was simulated using Matlab/Simulink and PSIM softwares. It was carried out an experimental assembly consisting of a 0.75 kW permanent magnet synchronous motor coupled to an electromagnetic brake as a mechanical load. The motor and load system were triggered by the inverter with space vector modulation. The results of the speed control, including reversal of speed and motor breaking, are presented in the study. The performance of a three level inverter using space vector modulation is compared to the performance of a two level inverter using space vector modulation feeding a resistive load. The simulation and experimental results are presented. In this work a qualitative comparison between the two level inverter and three level inverter was done showing in wich situations it is better to use the three level inverter<br>Mestrado<br>Energia Eletrica<br>Mestre em Engenharia Elétrica
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Dai, Ning Yi. "A generalized 3D pulse width modulator for multi-level voltage source inverters in three-phase four-wire power systems." Thesis, University of Macau, 2007. http://umaclib3.umac.mo/record=b2151603.
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Pinďák, Michal. "Třífázový střídač pro napájení vysokootáčkového asynchronního motor." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2018. http://www.nusl.cz/ntk/nusl-376934.
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The goal of this master´s thesis is primarily the theoretical analysis of three-phase inverters and subsequent familiarization of the reader with their detailed practical structure. The first part is devoted to the general definition of the power semiconductor converter as such. The following part describes the principle of three-phase pulse width modulation including the widely used principle of scalar control of induction motors. The second half of the thesis is already focused on the practical design of a three-phase inverter for a 50 kW high-speed induction motor. This section explains the problem of sizing and selecting all of the sub-elements of the inverter based on the parameters specified by the end user of the device.
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Alepuz, Menéndez Salvador Simón. "Aportación al control del convertidor CC/CA de tres niveles." Doctoral thesis, Universitat Politècnica de Catalunya, 2004. http://hdl.handle.net/10803/6330.
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La presente tesis estudia, propone y realiza sus principales aportaciones en el campo del control para el convertidor CC/CA de tres niveles, sobre la topología denominada Neutral-Point-Clamped, aunque se puede extender a otras topologías y/o número de niveles. Se presenta una metodología de modelado que emplea funciones de conmutación de fase, el operador de promediado y la transformación D-Q, tal que los modelos obtenidos en el dominio D-Q contienen una información completa sobre la dinámica del sistema. La estrategia de conmutación se puede entender como una extensión de la estrategia PWM senoidal de dos a tres niveles. Esta estrategia es simple y no realiza el control de ninguna de las variables del sistema. En esta tesis, el controlador se encarga de regular todas las variables del sistema, incluido el equilibrio del bus de continua. Este es un enfoque diferente del convencional, donde el equilibrio del bus de continua se consigue mediante la elección adecuada de los estados redundantes del convertidor en la estrategia de conmutación, mientras que el resto de variables se regulan a través del controlador. Para la realización del controlador, se propone la técnica de control lineal multivariable LQR (Linear Quadratic Regulator), complementada con la técnica de control no lineal adaptativo denominada programación de ganancia (Gain Scheduling). Se presenta, además, una metodología de cálculo del controlador. Este control es versátil, abierto y adaptable. En cualquier caso, el controlador se puede adaptar a las necesidades concretas de cada aplicación. El cálculo del controlador se realiza mediante simulación con MatLab-Simulink. Los modelos matemáticos que emplean las funciones de conmutación del convertidor son aquellos que ofrecen un mejor compromiso entre velocidad de simulación y precisión. Para validar el control propuesto, se ha diseñado y construido un equipo experimental donde el controlador se ha mostrado aplicable, útil y eficaz en la regulación de las distintas cargas y aplicaciones experimentadas, incluso con carga no lineal, bajo diferentes condiciones de trabajo y variables a controlar, tanto en régimen permanente como en procesos transitorios. La rapidez y calidad de la respuesta transitoria es comparable a la de otros sistemas de control publicados. Es especialmente interesante el excelente control conseguido del equilibrio del bus de continua. Además, la robustez del control permite cancelar el error estacionario aunque diferentes parámetros del sistema presenten desviaciones significativas respecto los valores esperados. El uso de la programación de ganancia junto con la técnica LQR se ha mostrado muy efectivo, puesto que permite realizar diferentes tipos de control. Se ha comprobado la congruencia entre simulaciones y resultados experimentales obtenidos, lo que valida los modelos de simulación empleados y el proceso de diseño del controlador mediante simulación.<br>This dissertation study, propose and carry out the main contributions in the field of three-level inverter control, using the topology Neutral-Point-Clamped, although results can be extended to other topologies and/or number of levels. A procedure for modelling is presented, based on line-switching functions, moving average operator and D-Q transformation. Then, the obtained models in D-Q frame contain complete information about system dynamics. Switching strategy is simple and can be considered as an extension of two-level sinusoidal PWM to three level. The system variables are not controlled by the switching strategy. In this work, all the system variables are controlled by the regulator, including DC-link balance. This control approach is different than the conventional one, where DC-link balance is achieved by means of a proper selection of redundant states in the switching strategy, and the other variables are controlled by the regulator. The regulator is based on the multivariable linear control technique LQR (Linear Quadratic Regulator), in combination with the non-linear adaptive control technique Gain Scheduling. Moreover, a methodology for the calculation of the controller is presented. This controller is versatile, open and adaptable. However, the controller can be built depending on the concrete specifications of each application. The controller is calculated by means of simulation using MatLab-Simulink. The mathematical models based on the switching functions of the converter give the best trade-off between simulation speed and precision. In order to validate the proposed controller, an experimental prototype has been designed and implemented. Experimental results show that the controller is useful and effective for the regulation of different loads and applications, even with non-linear loads, different operation points and variables to control, in steady-state and transitory operation. Dynamic response speed and quality are similar to other control systems in the literature. The DC-link balance control achieved is specially interesting. Furthermore, steady-state error is cancelled due to the robustness of the controller, even though significant deviation of different system parameters are present. The use of Gain-Scheduling in combination with LQR is effective, allowing the calculation of regulators with different control strategies. Good agreement between simulations and experimental results has been found. This result validates simulation models and the design method for the controller, based on simulations.
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Alepuz, Menéndez Salvador Simón. "Aportació al control del convertidor CC/CA de tres nivells." Doctoral thesis, Universitat Politècnica de Catalunya, 2004. http://hdl.handle.net/10803/6330.
Full textAbstract:
La presente tesis estudia, propone y realiza sus principales aportaciones en el campo del control para el convertidor CC/CA de tres niveles, sobre la topología denominada Neutral-Point-Clamped, aunque se puede extender a otras topologías y/o número de niveles. Se presenta una metodología de modelado que emplea funciones de conmutación de fase, el operador de promediado y la transformación D-Q, tal que los modelos obtenidos en el dominio D-Q contienen una información completa sobre la dinámica del sistema. La estrategia de conmutación se puede entender como una extensión de la estrategia PWM senoidal de dos a tres niveles. Esta estrategia es simple y no realiza el control de ninguna de las variables del sistema. En esta tesis, el controlador se encarga de regular todas las variables del sistema, incluido el equilibrio del bus de continua. Este es un enfoque diferente del convencional, donde el equilibrio del bus de continua se consigue mediante la elección adecuada de los estados redundantes del convertidor en la estrategia de conmutación, mientras que el resto de variables se regulan a través del controlador. Para la realización del controlador, se propone la técnica de control lineal multivariable LQR (Linear Quadratic Regulator), complementada con la técnica de control no lineal adaptativo denominada programación de ganancia (Gain Scheduling). Se presenta, además, una metodología de cálculo del controlador. Este control es versátil, abierto y adaptable. En cualquier caso, el controlador se puede adaptar a las necesidades concretas de cada aplicación. El cálculo del controlador se realiza mediante simulación con MatLab-Simulink. Los modelos matemáticos que emplean las funciones de conmutación del convertidor son aquellos que ofrecen un mejor compromiso entre velocidad de simulación y precisión. Para validar el control propuesto, se ha diseñado y construido un equipo experimental donde el controlador se ha mostrado aplicable, útil y eficaz en la regulación de las distintas cargas y aplicaciones experimentadas, incluso con carga no lineal, bajo diferentes condiciones de trabajo y variables a controlar, tanto en régimen permanente como en procesos transitorios. La rapidez y calidad de la respuesta transitoria es comparable a la de otros sistemas de control publicados. Es especialmente interesante el excelente control conseguido del equilibrio del bus de continua. Además, la robustez del control permite cancelar el error estacionario aunque diferentes parámetros del sistema presenten desviaciones significativas respecto los valores esperados. El uso de la programación de ganancia junto con la técnica LQR se ha mostrado muy efectivo, puesto que permite realizar diferentes tipos de control. Se ha comprobado la congruencia entre simulaciones y resultados experimentales obtenidos, lo que valida los modelos de simulación empleados y el proceso de diseño del controlador mediante simulación.<br>This dissertation study, propose and carry out the main contributions in the field of three-level inverter control, using the topology Neutral-Point-Clamped, although results can be extended to other topologies and/or number of levels. A procedure for modelling is presented, based on line-switching functions, moving average operator and D-Q transformation. Then, the obtained models in D-Q frame contain complete information about system dynamics. Switching strategy is simple and can be considered as an extension of two-level sinusoidal PWM to three level. The system variables are not controlled by the switching strategy. In this work, all the system variables are controlled by the regulator, including DC-link balance. This control approach is different than the conventional one, where DC-link balance is achieved by means of a proper selection of redundant states in the switching strategy, and the other variables are controlled by the regulator. The regulator is based on the multivariable linear control technique LQR (Linear Quadratic Regulator), in combination with the non-linear adaptive control technique Gain Scheduling. Moreover, a methodology for the calculation of the controller is presented. This controller is versatile, open and adaptable. However, the controller can be built depending on the concrete specifications of each application. The controller is calculated by means of simulation using MatLab-Simulink. The mathematical models based on the switching functions of the converter give the best trade-off between simulation speed and precision. In order to validate the proposed controller, an experimental prototype has been designed and implemented. Experimental results show that the controller is useful and effective for the regulation of different loads and applications, even with non-linear loads, different operation points and variables to control, in steady-state and transitory operation. Dynamic response speed and quality are similar to other control systems in the literature. The DC-link balance control achieved is specially interesting. Furthermore, steady-state error is cancelled due to the robustness of the controller, even though significant deviation of different system parameters are present. The use of Gain-Scheduling in combination with LQR is effective, allowing the calculation of regulators with different control strategies. Good agreement between simulations and experimental results has been found. This result validates simulation models and the design method for the controller, based on simulations.
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Dai, Min. "Control of power converters for distributed generation applications." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1124329850.
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Bouarfa, Abdelkader. "Méthodes de commande par allocation de convertisseurs statiques polyphasés, multi-niveaux : de la modélisation à la mise en oeuvre temps-réel." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30261/document.
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Dans nos travaux, nous nous intéressons à la commande des convertisseurs statiques à grand nombre d'interrupteurs. Le développement des topologies multi-niveaux multi-bras a ouvert l'accès aux domaines de la forte puissance et de la haute qualité harmonique. Outre cette montée en puissance, la commande spéciale de ces dispositifs permet de conférer au convertisseur des fonctionnalités avancées de plus en plus nécessaires, comme la possibilité de filtrage actif des harmoniques, la tolérance aux pannes, la gestion du réactif, les liaisons HVDC, etc. Toutefois, un plus grand nombre d'interrupteurs au sein d'une même structure de conversion se traduit par une forte croissance du nombre de variables de commande, des degrés de liberté et par une explosion combinatoire du nombre de configurations possibles. La synthèse de lois de commande suivant les approches traditionnellement conçues pour les topologies classiques, comme les méthodes de modulation vectorielle fondées sur la représentation géométrique du convertisseur, en devient rapidement fastidieuse pour les nouvelles topologies plus complexes. De plus, les interrupteurs présents en surnombre apportent des redondances fortes qui ne sont pas nécessairement exploitées, ou du moins arbitrairement. Nous proposons une nouvelle approche de commande qui se veut moins dépendante du nombre d'interrupteurs, et qui s'affranchit des limitations induites par les méthodes de modulation géométrique. Notre approche consiste dans un premier temps à formuler de manière algébrique des problèmes de commande qui sont généralement sous-déterminés, témoignant de la présence de redondances ou degrés de liberté, et contraints, car tenant compte des limitations propres aux rapports cycliques. De manière intéressante, ces problèmes offrent une similarité avec les problèmes dits d'allocation de commande rencontrés en aéronautique, en marine ou en robotique. Dans un second temps, dans le but de fournir à chaque période de découpage une solution de commande unique et optimisée, nous concevons de nouvelles méthodes d'allocation pour les convertisseurs statiques fondées sur l'optimisation numérique en ligne à partir de techniques d'optimisation linéaire. En conséquence, les rapports cycliques sont automatiquement optimisés pour satisfaire aux références de tension tout en respectant les saturations et en exploitant les redondances disponibles selon l'état actuel du convertisseur. Nous mettons en lumière les propriétés naturellement offertes par nos méthodes. Notamment, toutes nos solutions de modulation étendent de manière maximale la zone de linéarité du convertisseur. Nous proposons des méthodes d'allocation pour la commande en tension ou en courant de topologies variées : l'onduleur quatre bras deux niveaux, l'onduleur multicellulaire à condensateurs flottants, l'onduleur modulaire multi-niveaux. Concernant les convertisseurs multicellulaires, nos méthodes d'allocation utilisent automatiquement les degrés de liberté disponible pour fournir un équilibrage actif très rapide des tensions de condensateurs flottants. Aussi, grâce à la formulation algébrique des contraintes de commande, nos algorithmes peuvent prendre en compte un défaut sur un interrupteur pour conférer au convertisseur une propriété de tolérance aux fautes du point de vue de la commande<br>In our works, we are interested in control of high-switch-count power converters. The development of multileg, multilevel converters has opened the access to high power and high harmonic quality. The special control of these devices brings to the converter advanced abilities that are more and more requested nowadays, like active harmonic filtering, fault tolerance, active and reactive power transfer, High Voltage Direct Current (HVDC) links, etc. However, a higher number of switches in a conversion structure leads to a higher number of control variables, as well as more redundancies and a combinatorial explosion of the number of possible configurations. The development of control laws resulting from approaches traditionally designed for classical topologies, as for space vector modulation methods, becomes harder for new, much complex topologies. Moreover, the too many available switches bring strong control redundancies that are not necessarily exploited, at least arbitrarily. We propose a new control approach that is expected to be less dependent on the number of switches, and that does not suffer from limitations proper to geometrical modulation methods. Firstly, our approach consists in the algebraic formulation of control problems that are generally under-determined, highlighting the presence of redundancies and degrees of freedom, and constrained, because control limitations are taken into account. Interestingly, a connection can be highlighted to the so-called control allocation problem in flight control, robotics, or marine applications. Secondly, in order to compute a unique and optimized control solution at each switching period, we develop new control allocation methods for power converters based on on-line numerical optimization using linear programming techniques. Consequently, duty cycles are automatically optimized to satisfy voltage references while respecting saturations and exploiting available redundancies depending on the state of the converter. We highlight the properties naturally offered by our methods. In particular, all modulation solutions yield a maximized extension of the linearity range of the converter. We propose control allocation methods for the voltage or current control of many topologies: the four-leg two-level inverter, the multicellular flying capacitor inverter, the modular multilevel inverter
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Tarnoff, David. "Episode 1.4 – Pulse Width Modulation." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/computer-organization-design-oer/6.
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Sukovatý, Adam. "Vliv frekvenčního měniče na životnost ložisek a jejich poškození." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378732.
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This thesis deals with the effect of frequency inverter on the lifetime of roller bearings. The measurement has been carried out on the frequency inverter and induction motor by Siemens in the Switchgear laboratory of Fakulty of elektrical engineering and communication. Data has been recorded and processed on Adash VA4 Pro analyzer. Methods of measuring RMS values and frequency analysis of vibration and current were used for the analysis. Based on the mutual similarity of frequency spectrum, the presence of the high frequency capacitive current in the bearings has been proven. To prevent this, possible solutions have been presented. In the second part of the experiment an effect of changing pulse width modulation (PWM) on vibration was examined. The goal was to make a basic analysis and to provide background material for further research.
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Schrader, Johan Hendrik Rutger. "Wireline equalization using pulse-width modulation." Enschede : University of Twente [Host], 2007. http://doc.utwente.nl/58036.
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Wang, Xiao 1956. "Advances in pulse width modulation techniques." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=41210.
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The phase angle control of the Two-Level Sinusoidal Pulse Width Modulation (SPWM) strategy has been studied in Part I of this thesis, and applied to a new voltage-source type PWM High Voltage Direct Current (HVDC) transmission system. The PWM-HVDC station exercises direct control over the voltage phase angle, the amplitude and the frequency at the ac terminals using the phase angle lock loop (PLL) control of the SPWM. The parallel connection of multi-terminal PWM-HVDC stations can be achieved through simple local feedback control. The feasibility studies for the system, based on laboratory experiments and numerical analysis, are reported in the thesis.<br>In Part II of the thesis, the Three-Level SPWM technique has been studied and applied to the controls of a 3-chase, 6-valve, current-source PWM rectifier. A new Dynamic Three-Level SPWM strategy together with its Decoupler Pre-Processor has been proposed. The strategy enables each of three phase currents of the converter to be controlled independently and linearly, so that the dynamic feedback can be channelled. The Pole Placement control method has been implemented successfully, using a real-time digital control scheme. The scheme also succeeds in active filtering. The experimental results are obtained from a 1-KVA size laboratory model with a real-time controller using three TMS320C25 DSPs. The three DSPs operating in parallel are necessary to compute the feedback algorithms with minimum delays so as to ensure sufficient frequency bandwidth.
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Alvarenga, Marcos Balduino de 1967. "Estratégia de modulação PWM aplicada em conversores multiníveis tipo cascata simétrica para o balanceamento das tensões nos barramentos CC e minimização das comutações." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/260864.
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Orientador: José Antenor Pomilio<br>Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação<br>Made available in DSpace on 2018-08-23T00:46:30Z (GMT). No. of bitstreams: 1
Alvarenga_MarcosBalduinode_D.pdf: 18917931 bytes, checksum: a0630621c255135a8bf5fd49974daea6 (MD5)
Previous issue date: 2013<br>Resumo: Esta tese apresenta contribuições para o emprego de inversor multinível em cascata simétrica como filtro ativo de potência. O balanceamento das tensões nos barramentos CC é feito a partir de informação de um único bit obtido em cada módulo do conversor. O balanceamento é realizado através da postergação ou da supressão dos pulsos e, também, pela organização da ordem de acionamento das chaves semicondutoras de potência. A estratégia de modulação desenvolvida permite também a equalização dos pulsos de chaveamento entre os diversos módulos do inversor e suprime um porcentual de comutações redundantes ou irrelevantes, minimizando as perdas do conversor. Toma-se como parâmetro de qualidade a distorção harmônica decorrente de tais procedimentos. A técnica desenvolvida viabiliza a inserção de células em redundância, o que aumenta a confiabilidade da operação, favorecendo sua aplicação em filtros ativos de potência e dispositivos de condicionamento aplicados em redes de energia elétrica. O controle da corrente do filtro ativo e o controle das tensões nos barramentos CC são executados por dois controladores independentes, cujos projetos são detalhados e equacionados. A estratégia foi avaliada em um protótipo experimental de baixa tensão, constituído de um conversor multinível composto por quatro células simétricas, sendo uma em redundância, comandadas por um microcontrolador. Foram realizadas, também, simulações, considerando um alimentador de distribuição com 22,5 MVA e 13,8 kV. Nas análises dos resultados, são considerados os valores estabelecidos por normas relativas ao limite de harmônicas de corrente<br>Abstract: The present thesis shows contributions to the use of symmetrical cascaded multilevel inverter as active power filter. The balancing of the voltages on the DC bus is made from a single bit of information obtained in each converter module. Balancing is performed by postponement or suppression pulses and also for organizing the order of activation of the power semiconductor switches. The modulation strategy developed also allows the equalization of switching pulses between different inverter modules and removes a percentage of redundant or irrelevant switching, minimizing the losses of the converter. Taken as the quality parameter was the harmonic distortion resulting from such procedures. The technique developed enables the insertion of cells in redundancy, which increases reliability of the operation, in favor of their use in active power filters and conditioning devices used in power grids. The current control of active filter and control voltages in DC buses are performed by two independent controllers, whose projects are detailed and calculated. The strategy was evaluated in an experimental prototype low-voltage, consisting of a multilevel converter composed of four symmetrical cells, one redundancy, controlled by a microcontroller. It was also performed simulations considering a distribution feeder with 22.5 MVA and 13.8 kV. In the analysis of the results it was taken into account established values by standards for harmonic current limit<br>Doutorado<br>Energia Eletrica<br>Doutor em Engenharia Elétrica
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Boijort, Daniel, and Oskar Svanell. "Pulse Width Modulation for On-chip Interconnects." Thesis, Linköping University, Department of Electrical Engineering, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6341.
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<p>With an increasing number of transistors integrated on a single die, the need for global on-chip interconnectivity is growing. Long interconnects, in turn, have very large capacitances which consume a large share of a chip’s total power budget.</p><p>Power consumption can be lowered in several ways, mainly by reduction of switching activity, reduction of total capacitance and by using low voltage swing. In this project, the issue is addressed by proposing a new encoding based on Pulse Width Modulation (PWM). The implementation of this encoding will both lower the switching activity and decrease the capacitance between nearby wires. Hence, the total effective capacitance will be reduced considerably. Schematic level implementation of a robust transmitter and receiver circuit was carried out in CMOS090, designed for speeds up to 100 MHz. On a 10 mm wire, this implementation would give a 40% decrease in power dissipation compared to a parallel bus having the same metal footprint. The proposed encoding can be efficiently applied for global interconnects in sub-micron systems-on-chip (SoC).</p>
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Tawil, Danny S. "Investigation of losses in pulse width modulation converters." Honors in the Major Thesis, University of Central Florida, 1995. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/147.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.<br>Bachelors<br>Engineering<br>Computer Engineering
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Sun, Ning. "A pulse-width-modulated controlled-transformer post regulator." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-01242009-063207/.
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Stark, Stefan. "Direct Digital Pulse Width Modulation for Class D Amplifiers." Thesis, Linköping University, Department of Electrical Engineering, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-8476.
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<p>Class D amplifiers are becoming increasingly popular in audio devices. The strongest reason is the high efficiency which makes it advantageous for portable battery-driven products.</p><p>Infineon Technologies is developing products in this area, and has recently filed a patent application regarding an implementation of a part of the class D amplifier. The aim of this Master’s thesis is to evaluate a digital open-loop implementation of a class D amplifier, using the pending patent solution, and discuss the differences from an analog closed-loop implementation.</p><p>The focus has been on generating a high resolution PWM signal with a relatively low clock frequency. To achieve this, a hybrid of a counter and a self-calibrating tapped delay-line are used as a pulse generator. A model of the pulse generator was developed which made it possible to study how sampling frequency and different types of quantization affected quality parameters such as THD and SNR. With the results from the model two systems were implemented and simulated in HDL and as circuit schematics.</p><p>The proposed digital open-loop class D amplifier was found to be useful in voice-band applications and for music. Since the open-loop structure suffers from poor rejection of power supply ripple, either error correction or a regulated power supply is needed. If much effort is put on the different parts of the amplifier the result can be really good but, depending on other constraints on the system, it may be simpler and less time consuming to use the analog circuit with feedback to achieve hi-fi quality.</p><p>In summary, the combination of a counter and a self-calibrating tapped delay-line as a pulse generator is very useful in high resolution low-power systems. To avoid errors the delay-line and calibration can be made very accurate but with the expense of higher power consumption and area. However, the technique benefits from the small and fast logic devices available in deep sub-micron process technologies, which may finally lead to an advantage in power consumption and cost over the closed-loop analog solution.</p>
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Jacobs, Deon. "Digital pulse width modulation for Class-D audio amplifiers." Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1574.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006.<br>Digital audio data storage mediums have long been used within the consumer
market. Today, because of the advancement of processor clock speeds and increased
MOSFET switching capabilities, digital audio data formats can be directly amplified
using power electronic inverters. These amplifiers known as Class-D have an
advantage over there analogue counterparts because of their high efficiency.
This thesis deals with the signal processing algorithms necessary to convert the
digital audio data obtained from the source to a digital pulse width modulated signal
which controls a full bridge inverter for audio amplification. These algorithms
address difficulties experienced in the past which prevented high fidelity digital pulse
width modulators to be implemented.
The signal processing algorithms are divided into modular blocks, each of
which are defined in theory, designed and simulated in Matlab® and then
implemented within VHDL firmware. These firmware blocks are then used to realize
a Class-D audio amplifier.
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Tomashevskyi, Roman, Viacheslav Kulichenko, and Nikolay Mahonin. "System for Flow Rate Regulation with Pulse-Width Modulation." Thesis, Kyiv polytechnic institute, 2014. http://repository.kpi.kharkov.ua/handle/KhPI-Press/7880.
Full textAbstract:
In article describes the concept of the flow control system for ozone-oxygen mixture, using the principles of pulse-width modulation. The basic equation for calculation of the system measurement channel are given. Experimental studies of such air channel system and its performance characteristics are describes. The possibility of using flow control system ozone-oxygen mixture in medical ozone is shown.
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Tian, Feng. "Pulse Frequency Modulation ZCS Flyback Converter in Inverter Applications." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4266.
Full textAbstract:
Renewable energy source plays an important role in energy co-generation and distribution. A traditional solar-based inverter system has two stages cascaded, which has simpler controller but low efficiency. A new solar-based single-stage grid-connected inverter system can achieve higher efficiency by reducing the power semiconductor switching loss and output stable and synchronizing sinusoid current into the utility grid. In Chapter 1, the characteristic I-V and P-V curve of PV array has been illustrated. Based on prediction of the PV power capacity installed on the grid-connected and off-grid, the trends of grid-tied inverter for DG system have been analyzed. In Chapter 2, the topologies of single-phase grid-connect inverter system have been listed and compared. The key parameters of all these topologies are listed in a table in terms of topology, power decoupling, isolation, bi-directional/uni-directional, power rating, switching frequency, efficiency and input voltage. In Chapter 3, to reduce the capacitance of input filter, an active filter has been proposed, which will eliminate the 120/100Hz low frequency ripple from the PV array's output voltage completely. A feedforward controller is proposed to optimize the step response of PV array output voltage. A sample and hold also is used to provide the 120/100Hz low frequency decoupling between the controller of active filter and inverter stage. In Chapter 4, the single-stage inverter is proposed. Compared with conventional two-stage inverter, which has two high frequency switching stages cascaded, the single-stage inverter system increases the system efficiency by utilizing DC/DC converter to generate rectified sinusoid voltage. A transformer analysis is conducted for the single-stage inverter system, which proves the transformer has no low-frequency magnetic flux bias. To apply peak current mode control on single-stage inverter and get unified loop gain, adaptive slope compensation is also proposed for single-stage inverter. In Chapter 5, a digital controller for single-stage inverter is designed and optimized by the Matlab Control Toolbox. A Psim simulation verified the performance of the digital controller design. In Chapter 6, three bi-directional single-stage inverter topologies are proposed and compared. A conventional single-stage bi-directional inverter has certain shortcoming that cannot be overcome. A modular grid-connect micro-inverter system with dedicated reactive energy processing unit can overcome certain shortcoming and increase the system efficiency and reliability. A unique controller design is also proposed. In Chapter 7, a PFM ZCS flyback inverter system is invented. By using half-wave quasi-resonant ZCS flyback resonant converter and PFM control, this topology completely eliminates switching loss. A detailed mathematical analysis provides all the key parameters for the inverter design. As the inductance of transformer secondary side get smaller, the power stage transfer function of PFM ZCS flyback inverter system demonstrates nonlinearity. An optimized PFM ZCS flyback DC/DC converter design resolves this issue by introducing a MOSFET on the secondary side of transformer. In Chapter 8, experimental results of uni-direcitonal single-stage inverter with grid-connection, bi-directional single-stage inverter and single-stage PFM ZCS flyback inverter have been provided. Conclusions are given in Chapter 9.<br>Ph.D.<br>School of Electrical Engineering and Computer Science<br>Engineering and Computer Science<br>Electrical Engineering PhD
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Gatu, Andreas, and Alexander Svensson. "Justerbar modell av transmissionsledning för elkraftsöverföring." Thesis, KTH, Data- och elektroteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-166735.
Full textAbstract:
Detta examensarbete har utförts på uppdrag av Terco. Tercos PST 2220Transmission Line and Distribution Module fungerar som en fysisk modellav ett verkligt transmissions- eller distributionsnät där fem olika typer av nätmed avseende på längd, spänningsnivå och skenbar effekt är möjliga. Idagfinns ett behov av en modell där användaren kan ställa in dessa parametrarså att modellen mer precist kan spegla vilka egenskaper det specifika nätethar. Här undersöks hur längden och dess inverkan på en ledning kan varierasi en modell.En presentation av hur transmissions- och distributionsnät fungerar ochbeskrivs teoretiskt lägger grunden till den modell och de två approximationersom kan beskriva ett helt näts egenskaper.Då R, L och C komponenterna behöver kunna varieras för att fysisktkunna realisera denna teoretiska modell undersöks vilka metoder som dettakan genomföras på. För detta undersöks två tillvägagångssätt, kaskadkopp-lad pi-modell och variabel aktiv-passiv reaktans.Flera aspekter som utrymme, kostnad och variabilitet gör att varia-bel aktiv-passiv reaktans är att föredra. Dess funktion som en varierbarspänningskälla, uppbyggd av switchar styrda med reglerteknik och puls-breddsmodulering gör att komponenterna R, L och C och dess egenskaperoch inverkan på en transmissionslinje kan åstadkommas. Resultatet är attde nödvändiga R,L,C komponenterna går att variera i storlek för att kunnaingå i en varierbar transmissionsledningsmodell.Resultatet och målen säkerställs med simuleringar där variabel aktiv-passiv reaktans visas kunna vidareutvecklas och praktiskt testas för att mo-dellera transmissions- och distributionsnät med olika längd. Nyckelord. Variabilitet, Inverterare, Impedans, DC-AC, Pulsbreddsmodu-lering, Övertoner, Transmissionsledning, Spänningsfall, Reaktiv effekt.<br>This diploma work has been carried out on behalf of Terco. TercosPST 2220 Transmission Line and Distribution Module works as a physicalmodel of a real transmission and distribution grid where five different typesof networks based on length, voltage and apparent effect are available. Thereis today a need of a model where the user self can adjust these parameters sothat the model more precisely can reflect the characteristics that the specificgrid has. Here it’s investigated how the length and its impact on a line canbe varied in a model.A presentation of how the transmission and distribution grid works andare described theoretically provides the basics for the different models thatcan describe a whole network and its properties.Since the R, L and C components needs to be able to be varied to be ableto physically realize this theoretical model, the different methods that thiscan be realized through are investigated. Two approaches are investigated,the cascaded pi-model and variable active-passive reactance (VAPAR).A number of aspects like space, cost and variability makes the variableactive-passive reactance the most suited solution. Its function as a variablevoltage source, made out of an four switches, operated with control techno-logy and pulse width modulation, makes it possible to imitate R, L and Csproperties and effect on a transmission line. The result is that the necessaryR,L,C components are made adjustable in order to be incorporated in aadjustable transmission lin model.The result and the goal are verified with simulations where variableactive-passive reactance is proved able for further development and practicaltests to model transmission and distribution lines with different length. Keywords. Variability, Inverter, Impedance, DC-AC, Pulse width modula-tion, Harmonics, H-bridge, Transmission line, Voltage drop, Reactive effect.
36
Yang, Hyoseok Daniel. "Full software AC servo controllers with dynamic pulse width modulation." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80025.
Full text
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Chen, Jia-Wei, and 陳佳偉. "Design of Random Pulse Width Modulation Inverter with Harmonic Feedback." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/vhbhr6.
Full textAbstract:
碩士<br>國立虎尾科技大學<br>機械與機電工程研究所<br>98<br>A modulation scheme for random harmonics sampling pulse width modulation (RHSPWM) inverter with harmonic feedback is proposed in this thesis to eliminate low-order harmonic and reduce the side-band harmonic acoustic noises. For motor driven by sinusoidal pulse width modulation (SPWM) inverter, the energy is concentrated on side-band harmonic which results in annoying noises due to mechanical vibration with inverter switching frequency below 20 kHz and electromagnetic interference (EMI) problems for electrical system. The proposed RHSPWM inverter is designed to reduce the uncomfortable acoustic noise and noise volume with the switching frequency.
A compressor for air-conditioner is used for experiment to verify the proposed SPWM with harmonic feedback. The results show that the side-band harmonic are spread-out and normalized and the acoustic noise volume (in db) is reduced as well.
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Das, Soumitra. "Study on Pulsewidth Modulation Techniques for a Neutral-Point-Clamped Voltage Source Inverter." Thesis, 2012. http://etd.iisc.ac.in/handle/2005/3169.
Full textAbstract:
Neutral-point-clamped (NPC) three-level inverter is capable of handling higher dc bus voltage and producing output waveform of better quality than a conventional two-level inverter. The main objective of the present work is to analyze the existing PWM schemes for two-level and three-level inverters in terms of line current ripple, and to design new PWM techniques for the NPC inverter to reduce line current distortion.
Various discontinuous PWM or bus-clamping PWM (BCPWM) methods for a two-level voltage source inverter are analyzed in terms of rms line current ripple, which is evaluated by integrating the error voltage (i.e. error between the applied and reference voltages). The BCPWM schemes can be broadly classified into continual-clamp PWM (CCPWM) and split-clamp PWM (SCPWM). It is shown that split-clamp PWM scheme leads to lower harmonic distortion than CCPWM scheme. Further, advanced bus-clamping PWM (ABCPWM) methods for a two-level inverter are also studied. These methods clamp each phase to the positive and negative DC terminals over certain intervals as in BCPWM schemes, and also switch each phase at double the nominal frequency in certain other intervals unlike in BCPWM. Analytical closed-form expressions are derived for the total rms harmonic distortion due to SCPWM, CCPWM and ABCPWM schemes.
Existing sinusoidal and bus-clamping PWM schemes for three-level NPC inverters are also analyzed in the space vector domain. These methods are compared in terms of line current ripple analytically as well as experimentally. As earlier, closed-form expressions are derived for the harmonic distortion factors corresponding to centered space vector PWM (CSVPWM) and the various BCPWM methods.
A three-level inverter can be viewed as an equivalent two-level inverter in each sixth of the fundamental cycle or hextant. This is widely used to simplify the control of an NPC inverter. Further, this approach makes it simple to extend the BCPWM and ABCPWM methods for two-level inverters to three-level inverters. Furthermore, the method of analysis of line current ripple for the two-level inverter can also be easily extended to the three-level case.
The pivot vector, which is half the length of the longest voltage vectors produced by the NPC inverter, acts as an equivalent null vector for the conceptual two-level inverter. Each pivot vector can be produced by two inverter states termed as “pivot states”. Typically, in continuous modulation methods for NPC inverter such as sinusoidal PWM and centered space vector PWM, the switching sequence (i.e. the sequence in which the voltage vectors are applied) begins and ends with the same pivot vector in each subcycle, which is equivalent to a half-carrier cycle. To be more precise, the switching sequence starts with one pivot state and ends with the other in each subcycle.
However, in case of BCPWM schemes, only one pivot state is used in a subcycle. The choice of pivot state results in a variety of BCPWM schemes for an NPC inverter. Different BCPWM schemes are evaluated in terms of rms line current ripple. The optimal BCPWM, which minimizes the rms current ripple, is determined for an NPC inverter, controlled as an equivalent two-level inverter.
Further, four new switching sequences are proposed here for a three-level inverter, controlled as a conceptual two-level inverter. These sequences apply the pivot vector only once, but employ one of the other two vectors twice within the subcycle. These four switching sequences are termed as “ABCPWM sequences” for three-level inverter. These sequences exploit the flexibility available in the space vector approach to PWM to switch a phase more than once in a subcycle, which results in the application of an active vector twice within the subcycle.
Influence of the proposed ABCPWM sequences on the line current ripple over a subcycle is studied. The various sequences are compared in terms of rms line current ripple over a subcycle. An analytical closed-form expression for rms line current ripple over a subcycle is derived in terms of reference magnitude, angle of reference voltage vector, and subcycle duration for each of the sequences. Further, closed-form expressions are also derived for the rms current ripple over a line cycle in terms of modulation index and subcycle duration, corresponding to the various sequences.
The four proposed ABCPWM sequences for the NPC inverter can be grouped into two pairs of sequences. Each pair of sequences is shown to perform better than the individual sequences, if the two sequences are employed in appropriate spatial regions. Hence, with these two pairs of sequences, two hybrid PWM schemes are proposed. Finally, a hybrid PWM technique is proposed which employs all five sequences (conventional and proposed four sequences) in spatial regions where each performs the best. This is termed as “five-zone hybrid PWM”. The total harmonic distortion (THD) in the motor current, pertaining to all the proposed schemes, is studied theoretically over the entire range of linear modulation.
The theoretical investigations are validated experimentally on a 2.2 kW, 415V, 4.9A, 50 Hz induction motor drive. The no-load current THD is measured over a range of fundamental frequency from 10 Hz to 50 Hz in steps of 2 Hz for the various PWM methods. Theoretical and experimental results bring out the reduction in current THD due to the proposed BCPWM schemes at fundamental frequencies of 45 Hz and above, compared to CSVPWM. The ABCPWM methods improve the performance at higher as well as lower modulation indices. Further improvement is achieved with the proposed five-zone hybrid PWM. At the rated frequency (50 Hz) of the drive, the improvement in line current distortion is around 36% with this hybrid PWM scheme over CSVPWM. The reduction in THD is also experimentally verified at different loads on the motor.
The difference between the top and bottom capacitor voltages is measured at various operating conditions, corresponding to CSVPWM and the proposed schemes. No significant difference is observed in the dc neutral voltage shifts with the different proposed schemes and CSVPWM method. Thus, the proposed methods improve the THD at low and high speed ranges without appreciable worsening of the dc voltage unbalance.
39
Das, Soumitra. "Study on Pulsewidth Modulation Techniques for a Neutral-Point-Clamped Voltage Source Inverter." Thesis, 2012. http://hdl.handle.net/2005/3169.
Full textAbstract:
Neutral-point-clamped (NPC) three-level inverter is capable of handling higher dc bus voltage and producing output waveform of better quality than a conventional two-level inverter. The main objective of the present work is to analyze the existing PWM schemes for two-level and three-level inverters in terms of line current ripple, and to design new PWM techniques for the NPC inverter to reduce line current distortion.
Various discontinuous PWM or bus-clamping PWM (BCPWM) methods for a two-level voltage source inverter are analyzed in terms of rms line current ripple, which is evaluated by integrating the error voltage (i.e. error between the applied and reference voltages). The BCPWM schemes can be broadly classified into continual-clamp PWM (CCPWM) and split-clamp PWM (SCPWM). It is shown that split-clamp PWM scheme leads to lower harmonic distortion than CCPWM scheme. Further, advanced bus-clamping PWM (ABCPWM) methods for a two-level inverter are also studied. These methods clamp each phase to the positive and negative DC terminals over certain intervals as in BCPWM schemes, and also switch each phase at double the nominal frequency in certain other intervals unlike in BCPWM. Analytical closed-form expressions are derived for the total rms harmonic distortion due to SCPWM, CCPWM and ABCPWM schemes.
Existing sinusoidal and bus-clamping PWM schemes for three-level NPC inverters are also analyzed in the space vector domain. These methods are compared in terms of line current ripple analytically as well as experimentally. As earlier, closed-form expressions are derived for the harmonic distortion factors corresponding to centered space vector PWM (CSVPWM) and the various BCPWM methods.
A three-level inverter can be viewed as an equivalent two-level inverter in each sixth of the fundamental cycle or hextant. This is widely used to simplify the control of an NPC inverter. Further, this approach makes it simple to extend the BCPWM and ABCPWM methods for two-level inverters to three-level inverters. Furthermore, the method of analysis of line current ripple for the two-level inverter can also be easily extended to the three-level case.
The pivot vector, which is half the length of the longest voltage vectors produced by the NPC inverter, acts as an equivalent null vector for the conceptual two-level inverter. Each pivot vector can be produced by two inverter states termed as “pivot states”. Typically, in continuous modulation methods for NPC inverter such as sinusoidal PWM and centered space vector PWM, the switching sequence (i.e. the sequence in which the voltage vectors are applied) begins and ends with the same pivot vector in each subcycle, which is equivalent to a half-carrier cycle. To be more precise, the switching sequence starts with one pivot state and ends with the other in each subcycle.
However, in case of BCPWM schemes, only one pivot state is used in a subcycle. The choice of pivot state results in a variety of BCPWM schemes for an NPC inverter. Different BCPWM schemes are evaluated in terms of rms line current ripple. The optimal BCPWM, which minimizes the rms current ripple, is determined for an NPC inverter, controlled as an equivalent two-level inverter.
Further, four new switching sequences are proposed here for a three-level inverter, controlled as a conceptual two-level inverter. These sequences apply the pivot vector only once, but employ one of the other two vectors twice within the subcycle. These four switching sequences are termed as “ABCPWM sequences” for three-level inverter. These sequences exploit the flexibility available in the space vector approach to PWM to switch a phase more than once in a subcycle, which results in the application of an active vector twice within the subcycle.
Influence of the proposed ABCPWM sequences on the line current ripple over a subcycle is studied. The various sequences are compared in terms of rms line current ripple over a subcycle. An analytical closed-form expression for rms line current ripple over a subcycle is derived in terms of reference magnitude, angle of reference voltage vector, and subcycle duration for each of the sequences. Further, closed-form expressions are also derived for the rms current ripple over a line cycle in terms of modulation index and subcycle duration, corresponding to the various sequences.
The four proposed ABCPWM sequences for the NPC inverter can be grouped into two pairs of sequences. Each pair of sequences is shown to perform better than the individual sequences, if the two sequences are employed in appropriate spatial regions. Hence, with these two pairs of sequences, two hybrid PWM schemes are proposed. Finally, a hybrid PWM technique is proposed which employs all five sequences (conventional and proposed four sequences) in spatial regions where each performs the best. This is termed as “five-zone hybrid PWM”. The total harmonic distortion (THD) in the motor current, pertaining to all the proposed schemes, is studied theoretically over the entire range of linear modulation.
The theoretical investigations are validated experimentally on a 2.2 kW, 415V, 4.9A, 50 Hz induction motor drive. The no-load current THD is measured over a range of fundamental frequency from 10 Hz to 50 Hz in steps of 2 Hz for the various PWM methods. Theoretical and experimental results bring out the reduction in current THD due to the proposed BCPWM schemes at fundamental frequencies of 45 Hz and above, compared to CSVPWM. The ABCPWM methods improve the performance at higher as well as lower modulation indices. Further improvement is achieved with the proposed five-zone hybrid PWM. At the rated frequency (50 Hz) of the drive, the improvement in line current distortion is around 36% with this hybrid PWM scheme over CSVPWM. The reduction in THD is also experimentally verified at different loads on the motor.
The difference between the top and bottom capacitor voltages is measured at various operating conditions, corresponding to CSVPWM and the proposed schemes. No significant difference is observed in the dc neutral voltage shifts with the different proposed schemes and CSVPWM method. Thus, the proposed methods improve the THD at low and high speed ranges without appreciable worsening of the dc voltage unbalance.
40
Baiju, M. R. "Investigations On Multilevel Inverter Topologies And Modulation Schemes For Induction Motor Drives." Thesis, 2004. https://etd.iisc.ac.in/handle/2005/1126.
Full text
41
Baiju, M. R. "Investigations On Multilevel Inverter Topologies And Modulation Schemes For Induction Motor Drives." Thesis, 2004. http://hdl.handle.net/2005/1126.
Full text
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Li, Chien-Hsinh, and 李建興. "Implementation of Space-Vector Pulse-Width-Modulation Inverter for Three-Phase Induction Motors." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/54609099884431307244.
Full textAbstract:
碩士<br>國立雲林科技大學<br>電機工程技術研究所<br>87<br>This thesis discusses the design and implementation of the three phase induction motor drive system using a space-vector pulse-width-modulation (SVPWM) strategy based on a voltage-source inverter(VSI). A variable frequency, variable voltage converter is applied for the system control in induction motors.
This thesis is separated in two sections. First section introduces the implementation of IGBT protection circuit. A gate voltage controlled protection circuit is proposed to cut off the high fault current within short-circuit withstand time(nearly 10 us). The proposed protection circuit features a simple circuit and no extra DC power supply, and provides good protection characteristics.
A digital control inverter for a three-phase induction motor is discussed in the second section. The inverter with voltage/frequency (V/F) control was developed and implemented on a TMS320F240 DSP-based platform. The SVPWM strategy is applied for the control of inverter to reduce the voltage and current harmonics in the inverter output and consequently provide a smooth operation of the induction motor. The proposed SVPWM algorithm is discussed. Results of analytical and experimental investigation provide a guideline for the design and improvement of V/F control method used in induction motor drives.
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張桄瑋. "Application of High Frequency Pulse Width Modulation Inverter to Contactless Power Transmission System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/41830471878174685459.
Full textAbstract:
碩士<br>國立彰化師範大學<br>電機工程學系<br>98<br>With the advances in the power electronics technology, the traditional power transmission is no longer limited to the contact method; contactless power transmission can be another choice. Contactless power transmission is similar to a transformer, and air gap or magnetic flux leakage is a factor to power transmission quality. Thus, increasing the current efficiency leads to better transmission efficiency. This research has constructed a high-frequency 20kHz full-bridge inverter, and the input pulse signal was generated by using a microprocessor; multiple stage circuits are used in order to generate a 20kHz high frequency sinusoidal wave output. The high-frequency sinusoidal wave can therefore transmitted to the load by contactless method, and the method is based on electromagnetic coupling.
Keywords: Inverter, High-frequency sinusoidal, Power transmission
44
Yang, Chih-Hung, and 楊芷妅. "Design of Integrated Circuit of Pulse-Width Modulation Control for Three-Level Inverter." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/7t36hr.
Full textAbstract:
碩士<br>國立臺北科技大學<br>電機工程系研究所<br>97<br>The purpose of this thesis is to design and implement the control technique for the three-level inverter of induction motor by Application Specific Integrated-Circuit in TSMC .18μm technology. The three-level inverter employed is diode-clamped and we have conquered the problem of the voltage of the neutral point in balance. In this thesis a pulse-width modulation technique is presented which provides voltage balance between two DC-link capacitors and reduces the total harmonic distortion of output waveforms. The presented method requires voltage sensor only and can be realized based upon space vector modulation.
The simulation results are derived from Matlab®/Simulink®, and the experimental results are derived from an induction motor drive controlled by FPGA. The 12 signals of the inverter are controlled by a mechanism of Space Vector PWM, and feedback the voltage between the 2 capacitors to compensate the bias of the voltage of the neutral point. It will be shown that the simulation results and experimental results agree with other very well and confirming the performance of the presented control technique for three-level inverter. Finally we utilize EDA tools to design a cell-based integrated circuit system fulfilling the goals.
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Tripathi, Avanish. "Low Switching Frequency Pulse Width Modulation for Induction Motor Drives." Thesis, 2017. http://etd.iisc.ac.in/handle/2005/3688.
Full textAbstract:
Induction motor (IM) drives are employed in a wide range of industries due to low maintenance, improved efficiency and low emissions. Industrial installations of high-power IM drives rated up to 30 MW have been reported. The IM drives are also employed in ultra high-speed applications with shaft speeds as high as 500; 000 rpm. Certain applications of IM drives such as gas compressors demand high power at high speeds (e.g. 10 MW at 20; 000 rpm).
In high-power voltage source inverter (VSI) fed induction motor drives, the semiconductor devices experience high switching energy losses during switching transitions. Hence, the switching frequency is kept low in such high-power drives. In high-speed drives, the maximum modulation frequency is quite high. Hence, at high speeds and/or high power levels, the ratio of switching frequency to fundamental frequency (i.e. pulse number, P ) of the motor drive is quite low.
Induction motor drives, operating at low-pulse numbers, have significant low-order volt-age harmonics in the output. These low-order voltage harmonics are not filtered adequately by the motor inductance, leading to high total harmonic distortion (THD) in the line current as well as low-order harmonic torques. The low-order harmonic torques may lead to severe torsional vibrations which may eventually damage the motor shaft. This thesis addresses numerous issues related to low-pulse-number operation of VSI fed IM drives. In particular, optimal pulse width modulation (PWM) schemes for minimization of line current distortion and those for minimization of a set of low-order harmonic torques are proposed for two-level and three-level inverter fed IM drives.
Analytical evaluation of current ripple and torque ripple is well established for the induction motor drives operating at high pulse numbers. However, certain important assumptions made in this regard are not valid when the pulse number is low. An analytical method is proposed here for evaluation of current ripple and torque ripple in low-pulse-number induction motor drives. The current and torque harmonic spectra can also be predicted using the proposed method. The analytical predictions of the proposed method are validated through simulations and experimental results on a 3:7-kW induction motor drive, operated at low pulse numbers. The waveform symmetries, namely, half-wave symmetry (HWS), quarter-wave symmetry (QWS) and three-phase symmetry (TPS), are usually maintained in induction motor drives, operating at low switching frequencies. Lack of HWS is well known to introduce even harmonics in the line current. Impact of three-phase symmetry on line current and torque harmonic spectra is analyzed in this thesis. When the TPS is preserved, there are no triplen frequency components in the line current and also no harmonic torques other than those of order 6, 12, 18 etc. While TPS ensures that the triplen harmonics in the three-phase pole voltages are in phase, these triplen frequency harmonics form balanced sets of three-phase voltages when TPS is not preserved. Hence, triplen frequency currents flow through the stator windings. These result in torque harmonics of order 2, 4, 6, 8, 10 etc., and not just integral multiples of 6. These findings are well supported by simulation and experimental results.
One can see that two types of pole voltage waveforms are possible, when all waveform symmetries (i.e. HWS, TPS and QWS) are preserved in a two-level inverter, These are termed as type-A and type-B waveforms here. Also, QWS could be relaxed, while maintain-ing HWS and TPS, leading to yet another type of pole voltage waveform. Optimal switching angles to minimize line current THD are reported for all three types of pole voltage wave-forms. Theoretical and experimental results on a 3:7-kW IM drive show that optimal type-A PWM and optimal type-B PWM are better than each other in different ranges of modulation at any given low pulse number. In terms of current THD, the optimal PWM without QWS is found to be close to the better one between optimal type-A and optimal type-B at any modulation index for a given P . A combined optimal PWM to minimize THD is proposed, which utilizes the superior one between optimal type-A and optimal type-B at any given modulation index and pulse number. The performance of combined optimal PWM is shown to be better than those of synchronous sine-triangle (ST) PWM and selective harmonic elimination (SHE) PWM through simulations and experiments over a wide range of speed.
A frequency domain (FD) based and another synchronous reference frame (SRF) based optimal PWM techniques are proposed to minimize low-order harmonic torques. The objective here is to minimize the combined value of low-order harmonic torques of order 6, 12, 18, ..., 6(N 1), where N is the number of switching angles per quarter cycle. The FD based optimal PWM is independent of load and machine parameters while the SRF based method considers both load and machine parameters. The offline calculations are much simpler in
case of FD based optimal PWM than in case of SRF based optimal PWM. The performance
of the two schemes are comparable and are much superior to those of synchronous ST PWM
and SHE PWM in terms of low-order harmonic torques as shown by the simulation and
experimental results presented over a wide range of fundamental frequency,
The proposed optimal PWM methods for two level-inverter fed motor drives to minimize
the line current distortion and low-order torque harmonics, are extended to neutral point clamped (NPC) three-level inverter fed drive. The proposed optimal PWM methods for the NPC inverter are compared with ST PWM and SHE PWM, having the same number of
switching angles per quarter. Simulation and experimental results on a 3:7-kW induction
motor drive demonstrate the superior performance of proposed optimal PWM schemes over ST PWM and SHE PWM schemes.
The di_erent optimal PWM schemes proposed for two-level and three-level inverter fed
drives, having di_erent objective functions and constraints, are all analyzed from a space vector perspective. The three-phase PWM waveforms are seen as a sequence of voltage
vector applied in each case. The space vector analysis leads to determination of optimal
vector sequences, fast o_ine calculation of optimal switching angles and e_cient digital
implementation of the proposed optimal PWM schemes. A hybrid PWM scheme is proposed
for two-level inverter fed IM drive, having a maximum switching frequency of 250 Hz. The
proposed hybrid PWM utilizes ST PWM at a _xed frequency of 250 Hz at low speeds. This
method employs the optimal vector sequence to minimize the current THD at any speed in
the medium and high speed ranges. The proposed method is shown to reduce both THD as well as machine losses signi_cantly, over a wide range of speed, compared to ST PWM
Position sensorless vector control of IM drive also becomes challenging when the ratio
of inverter switching frequency to maximum modulation frequency is low. An improved
procedure to design current controllers, and a closed-loop ux estimator are reviewed. These are utilized to design and implement successfully a position sensorless vector controlled IM drive, modulated with asynchronous third harmonic injected (THI) PWM at a constant switching frequency of 500 Hz. Sensorless vector control is also implemented successfully, when the inverter is modulated with synchronized THI PWM and the maximum switching frequency is limited to 500 Hz.
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Tripathi, Avanish. "Low Switching Frequency Pulse Width Modulation for Induction Motor Drives." Thesis, 2017. http://etd.iisc.ernet.in/2005/3688.
Full textAbstract:
Induction motor (IM) drives are employed in a wide range of industries due to low maintenance, improved efficiency and low emissions. Industrial installations of high-power IM drives rated up to 30 MW have been reported. The IM drives are also employed in ultra high-speed applications with shaft speeds as high as 500; 000 rpm. Certain applications of IM drives such as gas compressors demand high power at high speeds (e.g. 10 MW at 20; 000 rpm).
In high-power voltage source inverter (VSI) fed induction motor drives, the semiconductor devices experience high switching energy losses during switching transitions. Hence, the switching frequency is kept low in such high-power drives. In high-speed drives, the maximum modulation frequency is quite high. Hence, at high speeds and/or high power levels, the ratio of switching frequency to fundamental frequency (i.e. pulse number, P ) of the motor drive is quite low.
Induction motor drives, operating at low-pulse numbers, have significant low-order volt-age harmonics in the output. These low-order voltage harmonics are not filtered adequately by the motor inductance, leading to high total harmonic distortion (THD) in the line current as well as low-order harmonic torques. The low-order harmonic torques may lead to severe torsional vibrations which may eventually damage the motor shaft. This thesis addresses numerous issues related to low-pulse-number operation of VSI fed IM drives. In particular, optimal pulse width modulation (PWM) schemes for minimization of line current distortion and those for minimization of a set of low-order harmonic torques are proposed for two-level and three-level inverter fed IM drives.
Analytical evaluation of current ripple and torque ripple is well established for the induction motor drives operating at high pulse numbers. However, certain important assumptions made in this regard are not valid when the pulse number is low. An analytical method is proposed here for evaluation of current ripple and torque ripple in low-pulse-number induction motor drives. The current and torque harmonic spectra can also be predicted using the proposed method. The analytical predictions of the proposed method are validated through simulations and experimental results on a 3:7-kW induction motor drive, operated at low pulse numbers. The waveform symmetries, namely, half-wave symmetry (HWS), quarter-wave symmetry (QWS) and three-phase symmetry (TPS), are usually maintained in induction motor drives, operating at low switching frequencies. Lack of HWS is well known to introduce even harmonics in the line current. Impact of three-phase symmetry on line current and torque harmonic spectra is analyzed in this thesis. When the TPS is preserved, there are no triplen frequency components in the line current and also no harmonic torques other than those of order 6, 12, 18 etc. While TPS ensures that the triplen harmonics in the three-phase pole voltages are in phase, these triplen frequency harmonics form balanced sets of three-phase voltages when TPS is not preserved. Hence, triplen frequency currents flow through the stator windings. These result in torque harmonics of order 2, 4, 6, 8, 10 etc., and not just integral multiples of 6. These findings are well supported by simulation and experimental results.
One can see that two types of pole voltage waveforms are possible, when all waveform symmetries (i.e. HWS, TPS and QWS) are preserved in a two-level inverter, These are termed as type-A and type-B waveforms here. Also, QWS could be relaxed, while maintain-ing HWS and TPS, leading to yet another type of pole voltage waveform. Optimal switching angles to minimize line current THD are reported for all three types of pole voltage wave-forms. Theoretical and experimental results on a 3:7-kW IM drive show that optimal type-A PWM and optimal type-B PWM are better than each other in different ranges of modulation at any given low pulse number. In terms of current THD, the optimal PWM without QWS is found to be close to the better one between optimal type-A and optimal type-B at any modulation index for a given P . A combined optimal PWM to minimize THD is proposed, which utilizes the superior one between optimal type-A and optimal type-B at any given modulation index and pulse number. The performance of combined optimal PWM is shown to be better than those of synchronous sine-triangle (ST) PWM and selective harmonic elimination (SHE) PWM through simulations and experiments over a wide range of speed.
A frequency domain (FD) based and another synchronous reference frame (SRF) based optimal PWM techniques are proposed to minimize low-order harmonic torques. The objective here is to minimize the combined value of low-order harmonic torques of order 6, 12, 18, ..., 6(N 1), where N is the number of switching angles per quarter cycle. The FD based optimal PWM is independent of load and machine parameters while the SRF based method considers both load and machine parameters. The offline calculations are much simpler in
case of FD based optimal PWM than in case of SRF based optimal PWM. The performance
of the two schemes are comparable and are much superior to those of synchronous ST PWM
and SHE PWM in terms of low-order harmonic torques as shown by the simulation and
experimental results presented over a wide range of fundamental frequency,
The proposed optimal PWM methods for two level-inverter fed motor drives to minimize
the line current distortion and low-order torque harmonics, are extended to neutral point clamped (NPC) three-level inverter fed drive. The proposed optimal PWM methods for the NPC inverter are compared with ST PWM and SHE PWM, having the same number of
switching angles per quarter. Simulation and experimental results on a 3:7-kW induction
motor drive demonstrate the superior performance of proposed optimal PWM schemes over ST PWM and SHE PWM schemes.
The di_erent optimal PWM schemes proposed for two-level and three-level inverter fed
drives, having di_erent objective functions and constraints, are all analyzed from a space vector perspective. The three-phase PWM waveforms are seen as a sequence of voltage
vector applied in each case. The space vector analysis leads to determination of optimal
vector sequences, fast o_ine calculation of optimal switching angles and e_cient digital
implementation of the proposed optimal PWM schemes. A hybrid PWM scheme is proposed
for two-level inverter fed IM drive, having a maximum switching frequency of 250 Hz. The
proposed hybrid PWM utilizes ST PWM at a _xed frequency of 250 Hz at low speeds. This
method employs the optimal vector sequence to minimize the current THD at any speed in
the medium and high speed ranges. The proposed method is shown to reduce both THD as well as machine losses signi_cantly, over a wide range of speed, compared to ST PWM
Position sensorless vector control of IM drive also becomes challenging when the ratio
of inverter switching frequency to maximum modulation frequency is low. An improved
procedure to design current controllers, and a closed-loop ux estimator are reviewed. These are utilized to design and implement successfully a position sensorless vector controlled IM drive, modulated with asynchronous third harmonic injected (THI) PWM at a constant switching frequency of 500 Hz. Sensorless vector control is also implemented successfully, when the inverter is modulated with synchronized THI PWM and the maximum switching frequency is limited to 500 Hz.
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Kanchan, Rahul Sudam. "Investigations On PWM Signal Generation And Common Mode Voltage Elimination Schemes For Multi-Level Inverter Fed Induction Motor Drives." Thesis, 2005. https://etd.iisc.ac.in/handle/2005/1405.
Full text
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Kanchan, Rahul Sudam. "Investigations On PWM Signal Generation And Common Mode Voltage Elimination Schemes For Multi-Level Inverter Fed Induction Motor Drives." Thesis, 2005. http://etd.iisc.ernet.in/handle/2005/1405.
Full text
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Tzeng, Yun-Chi, and 曾筠棋. "Design of Random Harmonic Sampling Pulse Width Modulation Inverter for Motor Drive to Reduce Acoustic Noises." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/zfc765.
Full textAbstract:
碩士<br>國立虎尾科技大學<br>車輛工程系碩士班<br>102<br>This paper presents a random harmonic sampling pulse width modulation for motor inverter whose side-band acoustic harmonic noises are spread out and harmonic energy is not concentrated to reduce the noise caused by output voltage harmonics of inverter due to the high switching frequency. In each cycle, the switching pattern of inverter from the programmed PWM waveforms with distinct harmonic spectrum is randomly selected. A compressor is used for experiments to verify the proposed modulation method to reduce the acoustic noises and spread out the side-band harmonics noises.
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CHENG, TENG-YUAN, and 鄭登元. "T-S Fuzzy Controls of Three-Phase Bidirectional Inverter Based on Space-Vector Pulse Width Modulation." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/bd9keg.
Full textAbstract:
碩士<br>國立中正大學<br>電機工程研究所<br>107<br>The main purpose of this thesis is to design and implement Takagi-Sugeno (T-S) fuzzy controls of the three-phase bidirectional inverter based on space-vector pulse width modulation (SVPWM). The developed three-phase bidirectional inverter can be applied to micro-grid systems. Its operation modes include grid-connected mode and rectification mode. The switching type is based on SVPWM. Three-phase currents are divided into six sections. First, state equations are derived from equivalent circuits of inverter according to six sections. The current tracking capability is achieved by adding error integral terms. T-S fuzzy controller is designed on the concept of parallel distributed compensation (PDC). Stability of the T-S fuzzy control system is also analyzed. Next, the controller gain is obtained by Linear Matrix Inequality (LMI) to determine duty ratios of power switches in the inverter. Therefore, the objective of current control can be achieved. The control unit of three-phase bidirectional inverter is the microcontroller Renesas RX62T. Voltage and current signals are captured as feedback into the microcontroller. The duty ratios of switches are calculated via T-S fuzzy controller and utilized to drive six switches. Finally, the inverter performance in grid-connected mode and rectification mode is verified by experimental results.