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1
Krogemann, Markus. "The parallel resonant DC link inverter : a soft-switching inverter topology with PWM capability." Thesis, University of Nottingham, 1997. http://eprints.nottingham.ac.uk/13526/.
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Soft-switching inverters have over the last decade received a lot of attention by researchers owing to the reduction or virtual elimination of switching losses that these circuits can achieve. Possible improvements in EMC performance due to the reduced levels of dv/dt have among other advantages triggered the development of a still growing number of zero-voltage or zero-current switching inverter circuits. More recently, the trend seems to have shifted from continuously resonant systems over to quasi-resonant topologies due to advantages in terms of device stresses and PWM compatibility. In this work, continuously resonant as well as quasi-resonant techniques are reviewed. A quasi-resonant circuit will be implemented in a three-phase PWM inverter system controlled by a network of transputers. It will be examined to which degree the working principle of this Parallel Resonant DC Link (PRDCL) inverter affects the PWM compatibility and a suitable PWM strategy will be presented and implemented. The modified PWM technique shows output quality comparable to standard PWM methods while being fully compatible with the operation of the resonant link. The conversion efficiency and EMC performance of a PWM inverter drive based on the PRDCL circuit will be measured and compared to its hard-switched equivalent. It will be shown that improvements over hard-switching inverters are possible. However, the investigation of the PRDCL PWM inverter also reveals a number of drawbacks which limit the achievable switching frequency and adversely affect the conversion efficiency. Despite the many previous publications these problems have generally been overlooked in the past.
2
勞偉籌 and Wai-chau Lo. "A PWM inverter drive and control for electric vehicles." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1986. http://hub.hku.hk/bib/B31207376.
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Lo, Wai-chau. "A PWM inverter drive and control for electric vehicles /." [Hong Kong : University of Hong Kong], 1986. http://sunzi.lib.hku.hk/hkuto/record.jsp?B1232243X.
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McCarty, Michael James. "Determining the Optimum Operating Parameters of a Unipolar PWM Inverter." DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/287.
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This study presents a determination of the optimum operating parameters of a unipolar PWM inverter through theoretical and experimental analysis. The inverter is investigated in its simplest form without input DC-DC conversion or output filtering. The intent of this study is to understand the core of the inverter thoroughly before adding peripheral elements such as output filtering. Variations on the input voltage level and switching frequency were investigated to determine their impacts on the operation of the inverter and harmonics produced. Theoretical modeling and calculations confirmed by experimental measurements and analysis allow determination of the inverter operating conditions which allow highest converter efficiency with lowest distortion. Results suggest highest efficiency and lowest harmonic distortion is achieved at the lowest input voltage (just above the peak of the desired fundamental component) and lowest switching frequency independent of output power.
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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.
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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)
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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)
7
Bisulli, Lorenzo. "Progetto e analisi di tecniche di modulazione pwm per inverter trifase." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21387/.
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Lo scopo della tesi era quello di analizzare vari parametri delle principali modulazioni PWM per inverter trifase in modo da distinguere quali fossero le più efficienti o le più affidabili. A tale scopo, è stata dapprima effettuata una panoramica dell’inverter trifase e delle relative modulazioni.
Sono stati quindi scritti vari codici in Matlab per simulare le diverse tecniche di modulazione. Le modulazioni presentate in questo testo (con i rispettivi codici) sono: Sinusoidal PWM, THIPWM, SVPWM, DSVPWM (0,1,2,3,+,-), ASDSVPWM, Six-step (implementata solo per effettuare un confronto).
Al termine della creazione dei vari codici, le modulazioni sono state studiate attraverso uno schema di inverter trifase implementato su Simulink. Il circuito, oltre a permettere la visualizzazione delle varie tensioni e correnti in uscita, ha consentito di studiare varie figure di merito utili per l’obbiettivo. Le figure di merito studiate sono state: THD, ripple di corrente, tensione di modo comune, numero di switching e rendimento di conversione.
I risultati ottenuti hanno permesso di capire che le modulazioni meno efficienti sono la six-step (basso rendimento di conversione e THD troppo elevato) e la ASDSVPWM (distorsione troppo elevata nonostante i buoni parametri in potenza e ripple). Al contrario le modulazioni più efficienti sono la DSVPWM0 e la DSVPWM2 grazie alla loro bassa distorsione armonica e ai buoni parametri ottenuti nelle altre figure di merito. Tutte le altre modulazioni in termini di efficienza sono inferiori alle ultime due.
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Yatim, Abdul Halim bin Mohamed. "A microprocessor controlled three-phase insulated gate transistor PWM inverter drive." Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292639.
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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/.
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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.
10
Ad'doweesh, K. E. "A microprocessor based PWM inverter drive incorporating a three-phase induction motor." Thesis, University of Bradford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371459.
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Engku, Ariff E. A. R. B. "Space vector Pwm techniques for six-phase three-level inverter-fed drives." Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/7982/.
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In recent years, research in the area of multiphase drives has increased significantly. Having higher number of machine phases allows the current to be shared between the phases, thus reducing the current rating of power semiconductors used in the power converter. Additionally, if a multilevel inverter is used to drive the machine, the output voltage waveforms are going to be approximated closer toward sinusoidal waveforms, thus resulting in lower total harmonic distortion. Therefore, the combination of multiphase and multilevel technologies gives considerable benefits compared to conventional two-level three-phase drives. Unlike a carrier-based approach, which can be easily expanded to any number of converter voltage levels and any number of machine phases, the development of space vector algorithms is also reliant on the machine’s configuration. In other words, different drive topologies require their own unique space vector algorithms. In fact, the complexity of developing a space vector algorithm will dramatically increase with the increase of number of levels and/or number of phases. This thesis presents pulse width modulation techniques for two- and three-level asymmetrical and symmetrical six-phase drives with a single or two isolated neutral points configuration. However, since the modulation techniques for the drives with two isolated neutral points are based on the well-established modulation techniques for three-phase drives, more emphasis is given towards the development of modulation techniques for single neutral point case, particularly those that are based on space vector algorithm principles. In order to realise sinusoidal output phase voltage waveforms, several requirements and conditions have to be met. The requirements revolve around ensuring that the low order harmonics, which contribute to the machine losses, will not exist. Meanwhile, the conditions are more towards minimising the switching losses. All modulation techniques are verified through simulation, while those for three-level case are validated experimentally as well. Comparison and discussion of obtained simulation and experimental results, performance and complexity in terms of execution time of the developed modulation techniques, are presented. The equivalence between corresponding modulation techniques, which are based on the space vector algorithm and carrier-based approach are also established.
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Hussien, Zahrul Faizi. "Current control of three-phase PWM Inverter for flywheel energy storage system." Thesis, University of Southampton, 2000. https://eprints.soton.ac.uk/47946/.
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The thesis is concerned with the use of flywheel energy storage system (FESS) in utility load levelling application. The work presented consists of two parts, first, an evaluation of utility load levelling schemes with FESS as the energy storage medium, and second, the development of power electronic interface of FESS to the utility. The thesis presents a study to evaluate FESS load levelling schemes in a UK electricity supply and distribution company. It identifies and quantifies the costs and benefits of the schemes, and carries out a financial appraisal based on Net Present Value (NPV) and Internal Rate of Return (IRR) methods. The results indicate that the DSM schemes utilising FESS can be financially viable for a UK electricity supply and distribution business in a mass-produced (low-cost) FESS scenario, and provide FESS manufacturers and developers with cost goals for such applications. The conclusions drawn provide the motivation for further technical research undertaken within the programme of work. The main work presented is in the area of power electronic interface between FESS, as well as other energy storage devices or energy sources, and the utility for embedded generation. The thesis particularly focuses on the design of current controllers for an interface in the form of three-phase voltage-source pulsewidth modulated (VS-PWM) inverter connected to the utility via LCL filter. Two different current controller structures based on suboscillation current control method have been analysed and designed, aided by computer simulation studies carried out using a general purpose dynamic system simulation software, Matlab Simulink. General properties of a three-phase VS-PWM inverter have been investigated to establish a basic understanding of its operation. The phenomenon of phase interaction in a system with no neutral connection has been examined and the effect of practical inverter nonlinearities caused by interlock time delay (dead time) and on-state voltage drops of the semiconductor devices has been discussed. Various PWM current control techniques have been investigated, including the three-independent hysteresis current control, advanced hysteresis current control, suboscillation current control and space vector current control. The suboscillation current control method has been chosen as produces a well defined harmonic spectrum in the output current without the need for complicated computations and extensive hardware, and can be easily implemented in analogue to avoid problems •sampling and computation time delay generally associated with digital controllers. Fundamental appreciation of the suboscillation PWM technique has been established from analytical synthesis of the modulation process, providing a rational basis for the current controller and computer simulation model validation. An inherent disadvantage of the suboscillation control method has been found to be its limited controller gain, causing a steady-state error to and the effect of inverter nonlinearities to be quite significant. In the first current controller structure, a simple compensation has been utilised to enable the gain to be increased beyond the conventional limit. Simulation results show that the steady-state error the current waveform has been improved and the effect of inverter nonlinearities has been It also makes the current controller less susceptible to the inherently noisy environment, current controller has been experimentally built and tested to validate the simulation results and to validate the practical aspects of its implementation. In the second current controller structure, a cyclic feedback system based on Iterative Control (ILC) has been utilised to eliminate the periodic error in the current waveform. The structure is more complicated and the cyclic feedback system requires digital implementation. Simulation results indicate that the cyclic feedback system is effective in eliminating periodic error in the current waveform. Due to time constraints and hardware limitations, ital implementation of the system has not been possible but is recommended for future research.
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Issa, Rihman H. "An investigation of efficient control strategies for a PWM inverter driven induction motor." Thesis, Loughborough University, 1987. https://dspace.lboro.ac.uk/2134/11783.
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Recent developments in power electronics switching devices have led to significant improvements in AC drives which, coupled with the obvious advantages of squirrel-cage induction motors, have generated a customerled demand for an increase in AC drive performance. This thesis describes the design and construction of a 3-phase pulsewidth modulated inverter using gate turn-off (GTO) thyristor switching devices, which drives a 0.75 kW 3-phase squirrel-cage induction motor. The inverter control circuit comprises a purpose-built large-scale integrated circuit, which generates the 3-phase pwm drive signals and allows the output voltge and frequency to be varied independently. When operating in open-loop, the drive system is capable of reverse operation, and the maximum rate of acceleration and deceleration of the motor may be controlled. Compensation for resistive voltage drop is provided when the motor is running at low speed. An analogue closed-loop proportional-integral-derivative speed controller is described, and for efficient operation under both no-load and on-load conditions torque feedback is also included. This provision both reduces the no-load losses in the motor and improves the torque-speed characteristic under load conditions. The improved closed-loop performance also includes power factor correction when the motor is lightly loaded,.together with an automatic boost to the motor voltage when loads are applied at low speed. A comparison is made between the performance of the analogue system and a digital real-time control implemented using a microcomputer. A series of computer programs are presented which simulate the performance of the drive system and which are suitable for running on the University mainframe computer. The programs enable the effects of the modulation technique and the inverter frequency on the pwm inverter steady-state output to be studied, and the performance of the induction motor to be investigated. Throughout the work, the theoretical predictions are supported by considerable experimental results.
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Kamberis, Adam. "Adaptive control in the Walsh domain of a PWM inverter fed A.C. motor." Thesis, Manchester Metropolitan University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.316179.
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Ibrahim, Zulkifilie. "Fuzzy logic control of PWM inverter-fed sinusoidal permanent magnet synchronous motor drives." Thesis, Liverpool John Moores University, 2000. http://researchonline.ljmu.ac.uk/5058/.
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Femia, Antonio. "Tecnica di modulazione PWM per inverter multifase con minima distorsione della corrente in uscita." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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L’obbiettivo della tesi è lo studio di una tecnica di modulazione che riduca la distorsione (ripple) della corrente in uscita da un inverter multifase. A tal fine, è stata determinata la tecnica di modulazione ottima, che rende teoricamente minimo il valore efficace del ripple di corrente. La tecnica proposta agisce sulla componente di modo comune delle tensioni dell’ inverter, per la quale viene determinata un’espressione esplicita in forma chiusa.
Simulazioni e prove sperimentali confermano le previsioni teoriche.
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Yang, Jian. "Prediction of the power losses of PWM inverter drives for permanent magnet synchronous motors." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-06112009-063124/.
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Bourgeade, Adrien. "PWM control optimization of a two-level inverter : Application to electric and hybrid vehicles." Electronic Thesis or Diss., Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0045.
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Malgré les améliorations de topologies des convertisseurs DC/AC, l'onduleur à deux niveaux reste le "gold standard" dans l'industrie ceci pour de multiples raisons : simplicité, fiabilité, etc. Dans le cadre de cette thèse entre Centrale Nantes et Renault, de nouvelles commandes d'onduleur ont été développées afin d'améliorer les performances sans modifier la topologie du convertisseur. Pour cela, deux approches basées sur des commandes hors-ligne synchrones ont été proposées. Premièrement, celles qui relaxent la contrainte de symétrie angulaire entre phases, usuellement imposée au convertisseur. Deuxièmement, celles qui sont à porteuse triangulaire consistant à injecter une séquence homopolaire de fréquence triple dans la modulante. La conséquence de cette approche est une généralisation de l’injection d'harmonique classique de rang trois. Un calcul aux limites a permis de montrer l'existence d'une méthodologie facilement implantable, qui prend la forme d'une injection d’une dent de scie. Les deux approches revisitent les stratégies de commande par modulation de largeur d'impulsion (MLI) de la littérature grâce à des considérations simples à base de relaxation et d'extension de propriétés existantes. L'ensemble de ces stratégies améliorent significativement le taux de distorsion harmonique des tensions ou courants fournis par l'onduleur pour des fréquences de commutations synchrones faibles. Ces observations ont été réalisées en simulation et validées sur un banc expérimental de faible puissanceDespite improvements in DC/AC converter topologies, the two-level inverter remains the "gold standard" in the industry for many reasons: simplicity, reliability, etc. In this thesis between Ecole Centrale and Renault, new inverter controls have been developed to improve the performance without modifying the converter topology. For this purpose, two approaches based on synchronous off-line controls have been proposed. Firstly, an angular symmetry relaxation between phases usually imposed on the converter. Secondly triangular carrier based strategies, meaning injecting a triple frequency homopolar sequence into the modulating signal. The consequence of this approach has given rise to a generalization of the classical third harmonic injection. A calculation extension has shown the existence of an easily implementable methodology, which takes the form of a sawtooth injection. Both approaches revisit the pulse width modulation (PWM) control strategies of the literature with simple considerations based on relaxation and extension of existing properties. The advantage of all these strategies is that they improve significantly the harmonic distortion rate of the voltages or currents supplied by the inverter for low synchronous switching frequencies. These observations have been done in simulation and validated on a low power experimental bench
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Nipoti, Simone. "Studio e realizzazione di un inverter trifase a tre livelli." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6817/.
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Lo scopo di questa tesi è lo studio e la realizzazione di una specifica tipologia di inverter, l’inverter trifase a tre livelli di tipo Cascaded. Il primo capitolo descrive l’inverter a due livelli e quello multilivello, evidenziandone gli aspetti peculiari e le possibili applicazioni. Il secondo capitolo affronta nello specifico l’inverter a trifase a tre livelli, per il quale, nel terzo capitolo, ne è descritta una realizzazione pratica, costruita presso i laboratori del Dipartimento di Ingegneria Elettrica dell’Università di Bologna. Nel quarto capitolo vengono presentate alcune prove sperimentali effettuate sul sistema reale.
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Repčík, Juraj. "Využití obvodů FPGA ve víceúrovňových měničích." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-317131.
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Tento projekt zkoumá vybrané způsoby implementace víceúrovňových měničů do praxe. V předložené práci je do hloubky prezentována tzv. ANPC (Active Neutral Point Clamped) pětiúrovňová topologie. Autor se v práci zaměřuje zejména na návrh technického řešení experimentálního vzorku a implementaci řídicích algoritmů jako jsou aktivní řízení napětí na pomocném kondenzátoru nebo aktivní balancování vstupního kapacitního děliče. Pro aplikaci zmíněných struktur byl vybrán moderní digitální integrovaný obvod, který slučuje mikroprocesor a FPGA do jednoho systému. Výsledný měnič umožňuje autonomní provoz a umožňuje generovat přesné a stabilní výstupní napětí.
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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.
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Master of ScienceDepartment of Electrical and Computer Engineering
Behrooz Mirafzal
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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Un, Emre. "Common Mode Voltage And Current Reduction In Voltage Source Inverter Driven Three Phase Ac Motors." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609062/index.pdf.
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In this thesis various reduced common mode voltage (RCMV) pulse width modulation (PWM) techniques and active/passive common mode voltage (CMV) reduction methods for voltage source inverter driven three-phase AC motors are theoretically and practically investigated. A novel RCMV-PWM method, the near state PWM (NSPWM) method is proposed for operation at high modulation index. At low modulation index, a modified version of an existing RCMV-PWM method, AZSPWM1, termed as MAZSPWM, is proposed to mitigate the voltage reflection problem of the method. An optimum modulation algorithm combining NSPWM and MAZSPWM with seamless transition is proposed. The proposed RCMV-PWM methods significantly reduce CMV but they suppress common mode current (CMC) partially. Utilization of a common mode inductor together with RCMV-PWM methods is effective in suppressing the CMC. In the study, in addition to the CMV characteristics, various practical performance characteristics such as voltage linearity, inverter output current ripple, inverter DC-link current ripple, and output line-to-line voltage pulse pattern are also analyzed. The study involves analysis, computer simulations, and detailed laboratory experiments.
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Sun, Pengwei. "Cascade Dual-Buck Inverters for Renewable Energy and Distributed Generation." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/26637.
Full textAbstract:
Renewable energy and distributed generation are getting more and more popular, including photovoltaic modules (PV), wind turbines, and fuel cells. The renewable energy sources need the power electronics interface to the utility grid because of different characteristics between the sources and the grid. No matter what renewable energy source is utilized, inverters are essential in the microgrid system. Thanks to flexible modular design, transformerless connection, extended voltage and power output, less maintenance and higher fault tolerance, the cascade inverters are good candidates for utility interface of various renewable energy sources.
This dissertation proposes a new type of cascade inverters based on dual-buck topology and phase-shift control scheme. Compared to traditional cascade inverters, they have enhanced system reliability thanks to no shoot-through problems and lower switching loss with the help of using power MOSFETs. With phase-shift control, it theoretically eliminates the inherent current zero-crossing distortion of the single-unit dual-buck type inverter. In addition, phase-shift control can greatly reduce the ripple current or cut down the size of passive components by increasing the equivalent switching frequency.
An asymmetrical half-cycle unipolar (AHCU) PWM technique is proposed for dual-buck full-bridge inverter. The proposed approach is to cut down the switching loss of power MOSFETs by half. At the same time, this AHCU PWM leads to current ripple reduction, and thus reducing ripple-related loss in filter components. Therefore, the proposed PWM strategy results in significant efficiency improvement. Additionally, the AHCU PWM also compensates for the zero-crossing distortion problem of dual-buck full-bridge inverter. Several PWM techniques are analyzed and compared, including bipolar PWM, unipolar PWM and phase-shifted PWM, when applied to the proposed cascade dual-buck full-bridge inverter. It has been found out that a PWM combination technique with the use of two out of the three PWMs leads to better performance in terms of less output current ripple and harmonics, no zero-crossing distortion, and higher efficiency.
A grid-tie control system is proposed for cascade dual-buck inverter with both active and reactive power flow capability in a wide range under two types of renewable energy and distributed generation sources. Fuel cell power conditioning system (PCS) is Type I system with active power command generated by balance of plant (BOP) of each unit; and photovoltaic or wind PCS is Type II system with active power harvested by each front-end unit through maximum power point tracking (MPPT). Reactive power command is generated by distributed generation (DG) control site for both systems. Selective harmonic proportional resonant (PR) controller and admittance compensation controller are first introduced to cascade inverter grid-tie control to achieve better steady-state and dynamic performances.Ph. D.
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Štěpnička, Martin. "Střídavý zdroj se vzdáleným řízením." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242121.
Full textAbstract:
The project describes the design of controlled inverters or power generator simulating one phase of European or American distribution network. The generator is able to enter into an output signal of a certain fault conditions designed to testing the electromagnetic compatibility of connected devices. The text is divided into three main chapters. The first one deals with the design of the power generating low-frequency signal. The second part describes the power source used for this generator. In the third section describes the program management unit. End of text summarizes the results. The annex contains a schematic designs and printed circuit boards.
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Tuhý, Luboš. "Výukový modul pro měření v předmětu Výkonová elektronika 1." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220550.
Full textAbstract:
This thesis describes the design and implementation of the transistor inverter to the subject of power electronics first outcome of this thesis will transistorized inverter that will serve as a demonstration tool in laboratory practice course electrical power. The laboratory preparation, students will be able to virtually test your theory acquired knowledge of the issue. Part of the theoretical analysis will be proposed circuit simulation program through classes Spice.
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Narayanan, G. "Synchronised Pulsewidth Modulation Strategies Based On Space Vector Approach For Induction Motor Drives." Thesis, Indian Institute of Science, 1999. https://etd.iisc.ac.in/handle/2005/139.
Full textAbstract:
In high power induction motor drives, the switching frequency of the inverter is quite low due to the high losses in the power devices. Real-time PWM strategies, which result in reduced harmonic distortion under low switching frequencies and have maximum possible DC bus utilisation, are developed for such drives in the present work.
The space vector approach is taken up for the generation of synchronised PWM waveforms with 3-Phase Symmetry, Half Wave Symmetry and Quarter Wave Symmetry, required for high-power drives. Rules for synchronisation and the waveform symmetries are brought out. These rules are applied to the conventional and modified forms of space vector modulation, leading to the synchronised conventional space vector strategy and the Basic Bus Clamping Strategy-I, respectively. Further, four new synchronised, bus-clamping PWM strategies, namely Asymmetric Zero-Changing Strategy, Boundary Sampling Strategy-I, Basic Bus Clamping Strategy-II and Boundary Sampling Strategy-II, are proposed. These strategies exploit the flexibilities offered by the space vector approach like double-switching of a phase within a subcycle, clamping of two phases within a subcycle etc. It is shown that the PWM waveforms generated by these strategies cannot be generated by comparing suitable 3-phase modulating waves with a triangular carrier wave.
A modified two-zone approach to overmodulation is proposed. This is applied to the six synchronised PWM strategies, dealt with in the present work, to extend the operation of these strategies upto the six-step mode. Linearity is ensured between the magnitude of the reference and the fundamental voltage generated in the whole range of modulation upto the six-step mode. This is verified experimentally.
A suitable combination of these strategies leads to a significant reduction in the harmonic distortion of the drive at medium and high speed ranges over the conventional space vector strategy. This reduction in harmonic distortion is demonstrated, theoretically as well as experimentally, on a constant V/F drive of base frequency 50Hz for three values of maximum switching frequency of the inverter, namely 450Hz, 350Hz and 250Hz.
Based on the notion of stator flux ripple, analytical closed-form expressions are derived for the harmonic distortion due to the different PWM strategies. The values of harmonic distortion, computed based on these analytical expressions, compare well with those calculated based on Fourier analysis and those measured experimentally.
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Narayanan, G. "Synchronised Pulsewidth Modulation Strategies Based On Space Vector Approach For Induction Motor Drives." Thesis, Indian Institute of Science, 1999. http://hdl.handle.net/2005/139.
Full textAbstract:
In high power induction motor drives, the switching frequency of the inverter is quite low due to the high losses in the power devices. Real-time PWM strategies, which result in reduced harmonic distortion under low switching frequencies and have maximum possible DC bus utilisation, are developed for such drives in the present work.
The space vector approach is taken up for the generation of synchronised PWM waveforms with 3-Phase Symmetry, Half Wave Symmetry and Quarter Wave Symmetry, required for high-power drives. Rules for synchronisation and the waveform symmetries are brought out. These rules are applied to the conventional and modified forms of space vector modulation, leading to the synchronised conventional space vector strategy and the Basic Bus Clamping Strategy-I, respectively. Further, four new synchronised, bus-clamping PWM strategies, namely Asymmetric Zero-Changing Strategy, Boundary Sampling Strategy-I, Basic Bus Clamping Strategy-II and Boundary Sampling Strategy-II, are proposed. These strategies exploit the flexibilities offered by the space vector approach like double-switching of a phase within a subcycle, clamping of two phases within a subcycle etc. It is shown that the PWM waveforms generated by these strategies cannot be generated by comparing suitable 3-phase modulating waves with a triangular carrier wave.
A modified two-zone approach to overmodulation is proposed. This is applied to the six synchronised PWM strategies, dealt with in the present work, to extend the operation of these strategies upto the six-step mode. Linearity is ensured between the magnitude of the reference and the fundamental voltage generated in the whole range of modulation upto the six-step mode. This is verified experimentally.
A suitable combination of these strategies leads to a significant reduction in the harmonic distortion of the drive at medium and high speed ranges over the conventional space vector strategy. This reduction in harmonic distortion is demonstrated, theoretically as well as experimentally, on a constant V/F drive of base frequency 50Hz for three values of maximum switching frequency of the inverter, namely 450Hz, 350Hz and 250Hz.
Based on the notion of stator flux ripple, analytical closed-form expressions are derived for the harmonic distortion due to the different PWM strategies. The values of harmonic distortion, computed based on these analytical expressions, compare well with those calculated based on Fourier analysis and those measured experimentally.
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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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Talarico, Andrea. "Analisi di un inverter implementato mendiante tecnologie ad ampio bandgap." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25393/.
Full textAbstract:
Studio e simulazioni un inverter con diverse topologie e modulazioni PWM, impiegando 3 diverse tecnologie: MOSFET al Silicio, transistore al Nitruro di Gallio e MOSFET al Carburo di Silicio.
Le topologie prese in esame sono: Full-Bridge e HERIC.
Le modulazioni PWM prese in esame sono: bipolare, unipolare, semi-onda, ibrida.
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Pou, Félix Josep. "Modulation and control of three-phase PWM multilevel converters." Doctoral thesis, Universitat Politècnica de Catalunya, 2002. http://hdl.handle.net/10803/6327.
Full textAbstract:
La present tesi doctoral estudia els inversors trifàsics multinivell del tipus denominat de díodes de fixació (diode-clamped converters). Aquests convertidors poden generar tres o més nivells de tensió a cada fase de sortida, i normalment s'apliquen a sistemes de gran potència ja que poden treballar amb tensions majors que els inversors clàssics. L'anàlisi es centra fonamentalment en la topologia de tres nivells, tot i que també es realitzen contribucions per a convertidors de més nivells. Els principals objectius són la proposta de nous algorismes de modulació vectorial PWM de processat ràpid, l'estudi i la compensació dels efectes dels desequilibris de les tensions dels condensadors del bus de continua, i l'anàlisi de llaços de control avançat.S'han desenvolupat diversos models que han permès obtenir resultats de simulació de les tècniques de modulació i control proposades. A més, gràcies a l'estada d'un any de l'autor al Center for Power Electronics Systems (CPES) a Virginia Tech, USA, la tesi també inclou resultats experimentals que consoliden les conclusions i metodologies presentades. Les principals contribucions es resumeixen a continuació.
Es presenta un nou algorisme de modulació vectorial PWM que aprofita simetries del diagrama vectorial per a reduir el temps de processat. S'analitzen i es quantifiquen les oscil·lacions de tensió de baixa freqüència que apareixen en el punt central dels condensadors del convertidor de tres nivells. Aquesta informació permet dimensionar els condensadors donades les especificacions d'una determinada aplicació.
L'algorisme de modulació també s'aplica a convertidors de més nivells. Pel cas concret del convertidor de quatre nivells, es comprova l'existència de corrents continus en els punts mitjos dels condensadors que fan que els sistema sigui inestable. Es determinen gràficament les zones d'inestabilitat.
Es presenta un nou i eficient algorisme de modulació vectorial feedforward en el convertidor de tres nivells que és capaç de generar tensions trifàsiques de sortida equilibrades, malgrat l'existència de desequilibris en les tensions dels condensadors.
S'estudien els efectes negatius de càrregues lineals desequilibrades i càrregues no lineals en el control de les tensions dels condensadors. Es justifica que l'existència d'un quart harmònic en els corrents de càrrega pot inestabilitzar el sistema. És determina la màxima amplitud tolerable d'aquest harmònic.
S'estudia la millora en l'equilibrat de les tensions d'una connexió de dos convertidors de tres nivells al mateix bus de continua (back-to-back connection). Un exemple d'aplicació pràctica és la conversió AC/DC/AC per a l'accionament de motors d'alterna treballant amb factor de potència unitari.
Finalment s'aplica un controlador òptim al convertidor de tres nivells treballant com a rectificador elevador (boost). El llaç de control LQR (Linear Quadratic Regulator) es simplifica donat que la tasca d'equilibrat de les tensions dels condensadors es dur a terme en el mateix modulador.
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Al-Egli, Fares, and Moumin Hassan Mohamed. "Control, Design, and Implementation of Quasi Z-source Cascaded H-Bridge Inverter." Thesis, Linköpings universitet, Elektroniska Kretsar och System, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-152711.
Full textAbstract:
This report is about control, design and implementation of a low voltage-fed quasi Z-source three-level inverter. The topology has been interesting for photovoltaic-systems due to its ability to boost the incoming voltage without needing an extra switching control. The topology was first simulated in Simulink and later implemented on a full-bridge module to measure the harmonic distortion and estimating the power losses of the inverter. An appropriate control scheme was used to set up a shootthrough and design a three-level inverter. The conclusion for the report is that the quasi Z-source inverter could boost the DC-link voltage in the simulation. But there should be more consideration to the internal resistance of the components for the implementation stage as it gave out a lower output voltage than expected.
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MIGLIAZZA, Giovanni. "Studio di nuove soluzioni di Inverter a corrente impressa per sorgenti energetiche rinnovabili e per azionamenti elettrici in ambito aerospaziale." Doctoral thesis, Università degli studi di Modena e Reggio Emilia, 2020. http://hdl.handle.net/11380/1200383.
Full textAbstract:
In questo lavoro di tesi è stata analizzata una particolare architettura di convertitore elettronico di potenza DC/AC denominata CSI (“Current Source inverter”). Storicamente, questa topologia è stata largamente impiegata per l’azionamento di macchine elettriche in media tensione. Il CSI, rispetto ai più diffusi Voltage Source Inverter (VSI) è caratterizzato da maggiori perdite di conduzione dei propri transistor ma è in grado di garantire un’affidabilità più elevata, siccome il corto-circuito di un qualunque mezzo-ponte (gamba dell’inverter) non determina una rottura (come nelle comuni architetture VSI), ma bensì è una normale condizione operativa all’interno di un periodo di commutazione della modulazione PWM. Una peculiarità importante di questa topologia è il suo funzionamento intrinseco come step-up nel caso la sorgente in ingresso al convertitore sia costituita da una sorgente di tensione continua seguita da un induttore. In questo lavoro si sono investigate modifiche topologiche rispetto all’architettura classica del CSI, nuove strategie di controllo e modulazioni PWM al fine di incrementare l’efficienza di conversione, ridurre il contenuto armonico indesiderato delle proprie correnti di uscita e limitare le correnti di modo comune. Cercando cosi, di rendere la topologia competitiva in applicazioni Industriali. Differenti soluzioni topologiche e di controllo del CSI sono state studiate per due differenti applicazioni: convertitori DC/AC grid-connected senza isolamento galvanico per sistemi fotovoltaici e per azionamenti elettrici per applicazioni aerospaziali. Nell’ambito dei convertitori DC/AC grid-connected sono state proposte soluzioni sia per sistemi trifase, sia per sistemi monofase. In particolare grazie all’aggiunta di uno o più transistor e a modulazioni PWM dedicate è stato possibile ridurre le perdite di conduzione, il contenuto armonico delle correnti iniettate in rete e la corrente di dispersione verso terra. Nella seconda applicazione come azionamento elettrico, si è investigato l’impatto della topologia nel mondo aerospaziale, proponendo una nuova strategia di controllo che permette di controllare la macchina elettrica unicamente attraverso un’architettura tradizionale CSI con sorgente di tensione continua e induttore serie, senza l’ausilio di un ulteriore convertitore DC-DC che regola la corrente in ingresso al CSI. Sfruttando la caratteristica intrinseca di innalzamento della tensione d’uscita dell’azionamento, sono stati progettati dei motori elettrici che potendo lavorare a tensioni più elevate e con basso contenuto armonico grazie al filtro d’uscita intrinseco del CSI, è possibile realizzare delle macchine con densità di potenza elevata, aspetto molto interessante in ambito aerospaziale.In this thesis work, a particular DC / AC power converter architecture called CSI ("Current Source inverter") was analyzed. Historically, this topology has been widely used for driving medium voltage electrical machines. The CSI, compared to the more widespread Voltage Source Inverter (VSI) is characterized by higher semiconductor conduction losses but is able to guarantee a higher reliability as the short-circuit of any half-bridge (inverter leg) does not cause a break (as in VSI architectures), but rather it is a normal operating condition within the pattern of PWM modulation. An important peculiarity of this topology is its intrinsic operation as voltage step-up when the input source of the converter consists of a DC voltage with an inductor in series. In this work, some topological variations respect to the classical CSI architecture were investigated along with new control strategies and Space Vector Modulation(SVM) in order to increase the conversion efficiency, to reduce the undesired harmonic component of output currents, and to mitigate the common mode current. Different CSI topologies and control strategies have been designed for two different applications: DC / AC grid-connected converters without galvanic isolation for photovoltaic applications and electric drives for aerospace applications. In Grid-connected applications, DC / AC converter solutions have been proposed for three-phase and single-phase systems. In particular, thanks to the addition of one or more transistors and dedicated SVM, it was possible to reduce conduction losses, the harmonic component in the injected currents into the grid and the ground leakage current. In the second application, the impact of the CSI topology in the aerospace environment was investigated. The proposed control strategy allows to control the electric machine using only the traditional CSI architecture with a DC Voltage source and with an inductor in series, without the aid of an additional DC-DC converter that regulates the input current of the CSI. Taking advantage of the intrinsic step-up voltage characteristic and very low high frequency harmonic content of the output phase voltages (thanks to the intrinsic CSI output filter), electric motors can be designed for higher voltages allowing higher power density, very interesting aspect in the aerospace field.
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Zavaglia, Gianluca. "Inverters multilivello per il pilotaggio di motori asincroni trifase." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/9747/.
Full textAbstract:
In questo lavoro di laurea si presentano le varie famiglie di convertitori multilivello MMC (Modular Multilevel Converter). Questi convertitori sono di ausilio per il condizionamento dei parametri di reti elettriche in media e alta tensione e possono anche essere convenientemente utilizzati nel pilotaggio di motori asincroni trifase. Dopo aver esplicitato i principi di funzionamento, presentato i dispositivi di commutazione, le tipologie conosciute e le rispettive principali tecniche di modulazione, si è presentato il motore asincrono trifase, il suo circuito equivalente e le problematiche di accoppiamento ad un inverter. Successivamente si è simulato un inverter multilivello di tipo Diode-Clamped, con modulazione analogica PWM multiportante, che aziona un motore asincrono commerciale, così da poterne verificare le prestazioni in diversi regimi di velocità.
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Billard, Thibaut. "Off-line and on-line partial discharges detection in low voltage motors of electric vehicle fed by a PWM inverter using non-intrusive sensor." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/2555/.
Full textAbstract:
Pour faire varier la vitesse d'un moteur d'une voiture électrique, un onduleur de tension avec une modulation de largeur d'impulsion (MLI) est utilisé. Les temps de commutation de plus en plus courts créent un grand nombre de fronts de tension. L'utilisation d'un onduleur sur une machine basse tension est de plus en plus répandue et peut provoquer une réduction de la durée de vie des machines. Tout d'abord, la répartition de la tension au sein de la bobine est fortement inhomogène à cause de la nature impulsionnelle de la tension. Dans des machines basse tension avec un bobinage en vrac, il y a donc une probabilité non négligeable que les quelques premières spires de la bobine supportant la tension lors de la commutation soient adjacentes avec les dernières, faisant ainsi supporter à l'isolation interspire une forte différence de potentiel. La désadaptation d'impédance entre les câbles de puissance et les bornes de la machine peuvent également générer des surtensions, augmentant encore la sollicitation sur l'isolation électrique. Dans ces conditions défavorables, des décharges partielles peuvent apparaitre et contribuer à la dégradation de l'isolation électrique, réduisant ainsi la durée de vie des machines. Pire encore, des moteurs ayant passé avec succès des essais de qualification en impulsionnel pour être alimentés par un onduleur de tension ont malgré tout des durées de vie réduites. Si de tels phénomènes sont facilement détectables en 50Hz, il devient difficile de les détecter de manière électrique avec un onduleur de tension avec l'amplitude et la variation du courant. De plus, l'onduleur de tension génère un bruit électromagnétique important perturbant les mesures avec les capteurs non-intrusifs. L'objectif de cette thèse est donc de développer une méthode de détection de décharges partielles, à l'aide d'un capteur non-intrusif, dans un moteur de voiture électrique alimenté par un onduleur de tension en on-line, ainsi qu'en off-line, afin de fournir des données pertinentes lors de la conception d'un moteur électrique, de test fin de chaine ou d'essai en fatigue. Pour atteindre cet objectif, une suite d'expériences montant en complexité ont permis de confronter le dispositif de détection à des conditions de plus en plus proches de celles d'une voiture électriqueTo control the speed of the motor in an electric vehicle, one solution is to use in the powertrain an inverter drive with pulse width modulation (PWM). This device is recreating a sinusoidal current on each phase with a high number of short pulses of the same amplitude but with a dynamic duty cycle. Recent advances in power electronics allowed switching time to be quicker and quicker thus creating voltage pulses with shorter and shorter rise time. The use of PWM inverter to fed low voltage is now widespread but not without posing well-known problems regarding the reliability of the machine. When an electric motor is fed with a very number of pulses per second, each pulse is not propagating immediately along the winding and thus the voltage distribution is not uniform as in the sinusoidal case. As a result, most of the voltage is located within the first turns of the coil during the first moment of the switching. When the motor is random wound, first and last turns of the same coil could be adjacent thus putting high demand on the turn-to-turn insulation. Impedance mismatch between power cables and motors terminals could lead to overvoltage which are increasing the electrical stress on the insulation system. In the worst-case scenario, partial discharges could occur and contribute to the gradual deterioration of the insulation materials thus leading to premature failure. If partial discharges are easily detected with sinusoidal voltage with standard testing procedure, it becomes much harder to so when the sample under test is fed by a PWM inverter drive. Indeed, it is very difficult to spot very low amplitude partial discharges signals among very large amplitude voltage and current. Moreover, the PWM inverter is generating electro-magnetical noise, which is highly disturbing in partial discharge detection using RF non-intrusive sensor. Worse still, some electric motors having passed successfully AC or repetitive impulses acceptance tests may still fail prematurely when fed by a PWM inverter drive. The aim of this Ph. D thesis is thus to develop a non-intrusive partial discharges detection method, using a non-intrusive sensor, off-line and on-line in an electric motor fed by a PWM inverter drive. To achieve this, a series of experiments, gradually growing in complexity, will test the detection method with harsher and harsher conditions, thus closer and closer to realistic electric vehicle operating conditions. From a single-phase test on an electric stator to a full-scale test on an industrial engine test bench, off-line and on-line detection proves to be possible. In addition, visual observations and experiments have been carried out to better understand the physics of the observed light emitting discharges
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Ustuntepe, Bulent. "A Novel Two-parameter Modulation And Neutral Point Potential Control Method For The Three-level Neutral Point Clamped Inverter." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606928/index.pdf.
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In this thesis, the neutral point potential drift/fluctuation of the three-level neutral
point clamped inverter is analyzed and a novel control algorithm, the two-parameter
PWM method is proposed to confine the neutral point potential variation to a very
small range. The two-parameter PWM method provides superior neutral point
potential control performance even with small DC bus capacitors. The method is
based on PWM pulse pattern modification and requires no additional hardware.
Detailed analytical models of the neutral point current and potential as a function of
the modulation parameters are established and the neutral point potential behavior is
thoroughly investigated. Based on the study, the deficiency of the known methods is
illustrated and the two-parameter PWM method is developed and its superior
performance demonstrated. The performance of the two-parameter PWM method is
verified by means of computer simulations utilizing both the per-PWM-cycle
average model and the detailed model of the inverter. The results are supported by
laboratory experiments involving both an R-L load and an induction motor drive.
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Ayhan, Ufuk. "Investigation Of Dc Bus Current Harmonics In Two And Three Level Three-phase Inverters." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614182/index.pdf.
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Within scope of this work, double-fourier analysis method of rapid calculation and
detailed simulation method, which are used to investigate DC bus current harmonics
in two level and three level three-phase inverters systematically, will be emphasized
and two methods will be compared via applying different modulation techniques. In
addition, DC bus currents will be investigated visually for various working
conditions and modulation methods. After that, analysis methods will be applied
and harmonic spectrums will be determined. After all, it will be showed that
calculated harmonic spectrums could be treated as unified harmonics around certain
frequencies and these unified harmonics could be reached easily via looking at
predetermined table. Moreover, it will also be showed that unified harmonic values
could be used to determine harmonic current components that are necessary for
sizing DC bus capacitor and could be used in various inverter analysis.
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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.
Full textAbstract:
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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Muñoz, Ramirez Oscar Mauricio. "Contributions on spectral control for the asymmetrical full bridge multilevel inverter." Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/8476.
Full textAbstract:
Las topologías de circuitos inversores multinivel pueden trabajar a tensiones y potencias mayores que las alcanzadas por convertidores convencionales de dos niveles. Además, la conversión multinivel reduce la distorsión armónica de las variables de salida y en algunos casos, a pesar del aumento de elementos de conmutación, también reduce las pérdidas de conversión al incrementarse el número de niveles. La reducción de distorsión alcanzada por el número de niveles puede aprovecharse para reducir las pérdidas de conmutación disminuyendo la frecuencia de las señales portadoras. Para reducir aún más esta frecuencia sin degradar el espectro, nosotros controlamos las pendientes de las portadoras triangulares. Primero se han desarrollado dos modelos analíticos para predecir el espectro del voltage de salida, dependiendo de: el índice de modulación MA, la razón de distribución de voltaje K de las fuentes de alimentación , y las cuatro pendientes de las portadoras{r1, r2, r3, r4}. El primer modelo considera el Muestreo Natural y se basa en Series Dobles de Fourier (SDF) mientras que el segundo modelo, utiliza la Serie Sencilla de Fourier (SSF) introduciendo el concepto de Muestreo Pseudo-Natural, una aproximación digital de la modulación natural. Ambos modelos son programados en Matlab, verificados con Pspice y validados con un prototipo experimental que contiene un modulador digital implementado con DSP.
La concordancia entre las modulaciones natural y pseudo-natural, asi como entre sus respectivos modelos, es aprovechada por un algorítmo genético (AG) donde la THD es la función costo a reducir. Después de varios ensayos y de sintonizar el AG, se genera una matriz que contiene conjuntos de portadoras optimizadas dentro un rango específico de las variables {MA,K} y es probada con un segundo prototipo en lazo cerrado. Un lazo lento digital modifica las portadoras creadas por un dsPIC en modulaciones PWM; estas son demoduladas y sus amplitudes corregidas por un lazo de acción anticipada. Estas portadoras se comparan con una referencia sinusoidal que a su vez es modificada por variables de estado, generando finalmente la modulación multinivel en lazo cerrado. Los resultados finales demuestran la fiabilidad de la reducción de armónicos usando la programación de las pendientes de las portadoras.
Palabras claves: inversor multinivel, PWM, distorsión armónica, modelo espectral, pendiente de portadora, conjunto de portadoras, distribución de niveles, Serie Doble de Fourier, Serie Simple de Fourier, muestreo natural, muestreo regular, muestreo pseudo-natural , Algoritmos Genéticos.
Multilevel inverter (MI) topologies can work at higher voltage and higher power than conventional two-level converters. In addition, multilevel conversion reduces the output variables harmonic distortion and, sometimes, in spite of the devices-count increment, the conversion losses can also decrease by increasing the number of levels. The harmonic distortion reduction achieved by increasing the number of levels, can be used to further reducing the switching losses by decreasing the inverter carrier frequencies. To reduce even more the switching frequency without degrading output spectrum, we control the triangular carrier waveforms slopes.
First, to achieve this target, two analytical models have been created in order to predict the inverter output voltage spectrum, depending on diverse parameters: the amplitude modulation index MA, the voltage distribution K of the inverter input sources, and the four carrier slopes {r1, r2, r3, r4}. The first model considers Natural Sampling and is based on Double Fourier Series (DFS) whereas the second model based on Simple Fourier Series (SFS), introduces the concept of Pseudo-Natural Sampling, as a digital approximation of the natural modulation. Both models are programmed in Matlab, verified with Pspice simulations and validated with a first experimental prototype with a DSP digital modulator.
The good agreement between natural and pseudo-natural modulations, as well as their respective DFS and SFS models, is exploited by a Genetic Algorithm (GA) application where THD is the cost function to minimize. After testing and properly tuning the GA, a framework matrix containing the optimized carriers set for a specific range of variables {MA,K} is generated and then, tested with a second, closed-loop prototype. A slow digital loop modifies the carrier slopes created by dsPIC microcontroller as PWM modulations, whose amplitude, once demodulated, are affected by a feed-forward loop. These carriers, compared with a sinusoidal reference, state-feedback modified, generate finally the closed-loop multilevel modulation. The final results demonstrates the feasibility of harmonic reduction by means of carrier slopes programming.
Keywords: multilevel inverter, PWM, harmonic distortion, spectral modeling, carrier slope, carriers set, level distribution, Double Fourier Series, Simple Fourier Series, natural sampling, regular sampling, pseudo-natural sampling, Genetic Algorithms.
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Yu, Huijie. "Driver Based Soft Switch for Pulse-Width-Modulated Power Converters." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/26399.
Full textAbstract:
The work in this dissertation presents the first attempt in the literature to propose the concept of â soft switchâ . The goal of â soft switchâ is to develop a standard PWM switch cell with built-in adaptive soft switching capabilities. Just like a regular switch, only one PWM signal is needed to drive the soft switch under soft switching condition.
The core technique in soft switch development is a built-in adaptive soft switching circuit with minimized circulation energy. The necessity of minimizing circulation energy is first analyzed. The design and implementation of a universal controller for implementation of variable timing control to minimize circulation energy is presented. The controller has been tested successfully with three different soft switching inverters for electric vehicles application in the Partnership for a New Generation Vehicles (PNGV) project. To simplify the control, several methods to achieve soft switching with fixed timing control are proposed by analyzing a family of zero-voltage switching converters.
The driver based soft switch concept was originated from development of a base driver circuit for current driven bipolar junction transistor (BJT). A new insulated-gate-bipolar-transistor (IGBT) and power metal-oxide-semiconductor field-effect-transistor (MOSFET) gated transistor (IMGT) base drive structure was initially proposed for a high power SiC BJT. The proposed base drive method drives SiC BJTs in a way similar to a Darlington transistor. With some modification, a new base driver structure can adaptively achieve zero voltage turn-on for BJT at all load current range with one single gate. The proposed gate driver based soft switching method is verified by experimental test with both Si and SiC BJT. The idea is then broadened for â soft switchâ implementation. The whole soft switched BJT (SSBJT) structure behaves like a voltage-driven soft switch. The new structure has potentially inherent soft transition property with reduced stress and switching loss.
The basic concept of the current driven soft switch is then extended to a voltage-driven device such as IGBT and MOSFET. The key feature and requirement of the soft switch is outlined. A new coupled inductor based soft switching cell is proposed. The proposed zero-voltage-transition (ZVT) cell serves as a good candidate for the development of soft switch. The â Equivalent Inductorâ and state plane based analysis method are used to simply the analysis of coupled inductor based zero-voltage switching scheme. With the proposed analysis method, the operational property of the ZVT cell can be identified without solving complicated differential equations. Detailed analysis and design is proposed for a 3kW boost converter example. With the proposed soft switch design, the boost converter can achieve up to 98.9% efficiency over a wide operation range with a single gate drive. A high power inverter with coupled inductor scheme is also designed with simple control compared to the earlier implementation. A family of soft-switching converters using the proposed â soft switchâ cell can be developed by replacing the conventional PWM switch with the proposed soft switch.Ph. D.
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Buyukkeles, Umit. "Improved Torque And Speed Control Performance In A Vector-controlled Pwm-vsi Fed Surface-mounted Pmsm Drive With Conventional P-i Controllers." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614294/index.pdf.
Full textAbstract:
In this thesis, high performance torque and speed control for a surface-mounted permanent magnet synchronous machine (PMSM) is designed, simulated and implemented. A three-phase two-level pulse width modulation voltage-source inverter (PWM-VSI) with power MOSFETs is used to feed the PMSM.
The study has three objectives. The first is to compensate the voltage disturbance caused by nonideal characteristics of the voltage-source inverter (VSI). The second is to decouple the coupled variables in the synchronous reference frame model of the PMSM. The last is to design a load torque estimator in order to increase the disturbance rejection capability of the speed control. The angular acceleration required for load torque estimation is extracted through a Kalman filter from noisy velocity measurements.
Proposed methods for improved torque and speed control performance are verified through simulations and experimental tests. The drive system is modeled in Matlab/Simulink, and control algorithms are developed based on this model. The experimental drive system comprises a three-phase VSI and a 385 W surface-mounted PMSM. Control algorithms developed in the study have been implemented in a digital signal processor (DSP) board and tested comprehensively. With the use of the proposed methods, a considerable improvement of torque and speed control performance has been achieved.
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Oliveira, Yuri Calil Loures de. "Alimentação de cargas hospitalares críticas utilizando conversores estáticos." Universidade Federal de Juiz de Fora, 2016. https://repositorio.ufjf.br/jspui/handle/ufjf/1398.
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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
Esta dissertação apresenta um estudo de estratégias de alimentação de cargas hospitalares críticas utilizando conversores estáticos de energia. As cargas hospitalares escolhidas foram os equipamentos de raio x, tomografia computadorizada e ressonância magnética, sendo comparadas as seguintes formas de integração à rede: (i) estrutura com um retificador trifásico conectado à rede e três inversores monofásicos conectados às cargas ou (ii) estrutura com três retificadores monofásicos conectados à rede e três inversores monofásicos conectados às cargas. Por questões de patente, houve dificuldade em se encontrar os circuitos de front-end das fontes de alimentação das cargas hospitalares. Logo, as mesmas foram construídas dentro do ambiente de simulação do software PSIM utilizando dados de medição obtidos na literatura. O controle dos retificadores trifásico e monofásico foi realizados utilizando duas malhas de controle em cascata, com a malha interna controlando a corrente consumida da rede e a malha externa regulando a tensão no barramento CC. Para os três inversores monofásicos de saída foram implementados os controles PI RES e PI SRF visando uma comparação quanto ao desempenho. Como forma de validar o modelo matemático do sistema e o algoritmo de controle, foram feitas simulações utilizando o software PSIM. A análise feita comprovou que os resultados de simulação se mostraram coerentes com a modelagem matemática do sistema.
This master thesis presents a study about feeding strategies of critical hospital loads through power static converters. The chosen hospital loads were the x ray equipment, the computed tomography and the magnetic resonance. The following forms of grid integration were compared: (i) structure with a three-phase rectifier connected to the network and three single-phase inverters connected to the loads or (ii) structure with three single-phase rectifiers connected to the network and three single-phase inverters connected to the loads. Due to patent issues, it was difficult to find the front-end circuits for power supplies of hospital loads. Therefore, the loads were implemented in PSIM software environment using measurement data obtained from literature. The control of three-phase and single-phase rectifiers was implemented using two cascaded control loops, with the inner loop controlling the current drawn from the network and the outer loop regulating the DC bus voltage. For the single-phase inverter, PI RES and PI SRF controls were implemented, targeting a comparison in terms of performance. In order to validate the mathematical model of the system and the control algorithm, simulations were performed using the PSIM software. The analysis showed that the simulation results were consistent with the mathematical modeling of the system.
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LIMA, Nelio Neves. "Operação do gerador de indução em conexão assíncrona com a rede monofásica." Universidade Federal de Goiás, 2010. http://repositorio.bc.ufg.br/tede/handle/tde/999.
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Previous issue date: 2010-03-26This text reports the effort to present a proposal of a power generation system based on cage rotor Induction Electrical Machine associated to a sinusoidally-switched PWM (Pulse Width Modulation) frequency converter responsible for maintaining constant 60 Hz frequency at the generator leads. DC side at the PWM converter is nonsynchronously connected to a single-phase utility line by means of a full-bridge current-fed thyristor inverter, employing a step-down DC-DC converter in order to turn the grid injected current into a sinusoidal waveform. The proposed system allows for the operation as cogenerator in sites fed by single-phase utility net where there is availability of energetic resources. The DC capacitor voltage (Vdc) is controlled through the DC side energy balance adjusting the amplitude of the active current sent to the utility grid. The control strategy employed was the analogic proportional-integral (PI) error compensation. The system is also able to act as reactive power compensator to the AC loads as the Cdc capacitor represents a voltage source to the inverter and the three-phase diode bridge allows for bidirectional power flow between AC and DC sides. Simulation and experimental results has corroborated system viability to provide three-phase balanced regulated voltages complying with ANEEL 505/2001 Resolution and with IEEE Std 519-1992.
Este trabalho apresenta a proposta de um sistema para geração de energia elétrica baseado na Máquina de Indução Trifásica (MIT) com rotor tipo gaiola de esquilo associada a um conversor de freqüência chaveado no modo PWM (modulação por largura de pulsos na sigla em inglês) senoidal. O lado CC do conversor de frequência é conectado assincronamente à rede monofásica da concessionária através de um inversor monofásico em ponte completa a tiristores, alimentado em corrente, e de um conversor CC-CC abaixador de tensão, utilizado para modular senoidalmente a corrente injetada na rede via inversor. Este sistema permite a operação como co-gerador em localidades alimentadas por linhas monofásicas e com disponibilidade de recursos energéticos. O conversor de freqüência é responsável por manter a freqüência fundamental nos terminais do gerador de indução fixa em 60 Hz. A tensão no capacitor Ccc (Vcc) é controlada através da manutenção do balanço energético no lado CC do conversor PWM, ajustando a amplitude da corrente ativa injetada na rede monofásica em um valor adequado. A estratégia empregada para implementação do controle foi a compensação analógica tipo proporcional-integral (PI) do erro de Vcc. O sistema é ainda capaz de atuar como compensador de potência reativa para as cargas CA, já que o capacitor Ccc representa uma fonte de tensão contínua para o inversor e a ponte trifásica a diodos permite o fluxo bidiredional de energia entre os lados CA e CC do sistema. Os resultados de simulação e experimentais sustentam a viabilidade do sistema para prover tensões trifásicas equilibradas e reguladas, satisfazendo os requisitos da resolução 505/2001 da ANEEL e da norma IEEE Std 519-1992 do IEEE/ANSI.
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Wang, Bo-Han, and 王柏翰. "Harmonic Elimination for PWM Inverter." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/93211412376861913471.
Full textAbstract:
碩士國立交通大學
機械工程系所
102
In this thesis, we discuss about a single-phase DC-AC pulse-width modulated (PWM) inverter system. Actually, the harmonics in the PWM inverter output voltage are often generated as a result of voltage source disturbances. The high-frequency harmonics will filter out by the system itself; nevertheless, the low-frequency harmonics induced by the fundamental component can cause the output ac current to be distorted. A Doubly Coprime Factorization Disturbance Observer (DCFDOB) structure is applied to the DC-AC inverter. This structure can reduce the influence between low-frequency harmonic、system uncertainties and output current without complicated calculations or adding extra circuit components. In implementation, we use the TI Piccolo TMS320F28035 DSP control card. Then the software part including operating procedure, function block, main code, analog-to-digital converter(ADC), interrupt service routine(ISR) and the complete software structure will be introduced. Find the place where DCFDOB control structure is added in the software structure. At last, the result of different condition will be shown and analyze the output current by FFT .
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Wang, Chi-Nam, and 王旗男. "Multilevel PWM Inverter Control Induction Motor." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/28752679261546760678.
Full textAbstract:
碩士國立雲林科技大學
電機工程系碩士班
89
This paper presents a five-level diode clamp inverter control for induction motor by using simple V/F control law. Multilevel voltage source inverter is based on the extension of two-level inverter. By using the multilevel pulse width modulation scheme, we can obtain better output voltage and current waveform with less harmonics. The advantage of multilevel inverter is using low rated power MOSFET to implement high voltage or high power applications. To implement the adopted multilevel scheme for induction motor , the computer simulations and hardware tests based on digital signal processor (TMS320C50) are presented in this thesis.
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陳宏亮. "Space vector PWM inverter for induction motor." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/80902045781543702812.
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Behera, Suryakant. "FPGA based PWM techniques for controlling Inverter." Thesis, 2010. http://ethesis.nitrkl.ac.in/1985/1/FPGA_based_PWM_techniques_for_controlling_Inverter.pdf.
Full textAbstract:
Pulse Width Modulation has nowadays become an integral part of every electronics system. These techniques have been widely accepted and are researched extensively nowadays. It has found its application in large number of applications as a voltage controller. Its use in controlling output voltage of Inverter is the most frequently used application. There are basically two main techniques of PWM Generation- Analog technique and Digital Technique.
This thesis deals with these two techniques. First Analog techniques were studied in detail but these techniques have some demerits. Due to these demerits digital techniques were studied. Various digital PWM Generator topologies were studied. The VHDL code for each of these topologies was written and synthesized using Xilinx ISE 10.1 software. Behavioral Simulation was performed on the architecture and after verifying the results this VHDL code was downloaded to SPARTAN 3E FPGA. After downloading the code in FPGA real time debugging was done for the architecture. The results were seen in Chipscope Pro software.
Also from Synthesis report generated after synthesizing the VHDL code of each digital PWM Generator topologies comparison was done between these topologies in terms of number of logic blocks used and device utilization of each architecture.
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Al-Ghubari, Fahad H. "Voltage analysis of PWM inverter fed induction motors." Thesis, 1999. http://hdl.handle.net/1957/33092.
Full textAbstract:
Adjustable Speed Drive (ASD) systems are widely used in industry to
effectively improve process efficiency and control. Typically, an ASD system consists
of a motor with its speed controlled by a power electronics converter via varying the
amplitude and frequency of the input voltage. However, several abnormal insulation
failures of random wound motors in ASD applications have been reported. These
failures were related to voltage transients caused by inverters employing fast insulated
Gate Bipolar Transistors (IGBTs) combined with long cables that connect motors to
inverters.
This thesis further analyzes the distribution of voltage waveforms generated by a
pulse-width modulated (PWM) inverter at the motor terminals and windings.
Experimental work was performed at the Motor Systems and Resource Facility (MSRF)
at Oregon State University on a specially made 5hp induction motor with taps from the
first and second coil and from the first four and last two turns in every phase. Tests were
performed with long and short cables and results are compared. A simple simulation
model was created in PSpice and used to predict maximum voltage transients across
coils and turns. The validation of the model is demonstrated by its capability to predict
most of the experimental results.Graduation date: 2000
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ZOU, YING-YU, and 鄒應嶼. "A research on digital PWM inverter modulation techniques." Thesis, 1987. http://ndltd.ncl.edu.tw/handle/46612047745572483588.
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wu, chin-chung, and 吳錦長. "Space-Vector PWM and Soft-Switching Inverter Design." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/31901818179071106165.
Full textAbstract:
碩士國立交通大學
電機與控制工程系
87
Soft-switching techniques ( zero current switching or zero voltage switching ) applied to power inverter can substantially improve the performances, allowing high frequency operation and minimization of acoustic noise and EMI, reduction of switching losses, limitation of dv/dt and di/dt stress in the power devices .The quasi-resonant dc link soft switching circuit used in this paper needs additional components such as two switches, a diode, an inductor and a capacitor, the two switches are also soft switching, which produces a minimum losses. The quasi-resonant dc link circuit notching the bus voltage and allowing the switches of the inverter just switching at zero voltage. The modulation technique we adapt is Space-Vector PWM and refuse traditional sinusoidal PWM, because the SPWM can't completely utilize the dc link voltage, current ripple is badly and analogical mode control, which is complex and not easy to maintain. Now the digitalization design has become the standard of the drive- controller, so the superior performance and easy-digitized SV-PWM has become major method in the PWM techniques. The control of the system are processed by the chips FLEX PF10KAL10LC C84-4 of Altera company. Whose hardware description language can scrimp the time in design and makes the system more easily to maintain and modify. The experiment results have shown that our soft-switching circuit works very stable and reliably.
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Hsu, Pao-Sheng, and 許堡勝. "A Synchronous PWM Controller for A CCFL Royer Inverter." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/84363382960434258762.
Full textAbstract:
碩士國立臺灣科技大學
電子工程系
93
This thesis presents a synchronous PWM controller for self-oscillation Royer inverter. The dead-time-modulated PWM (DTM-PWM) controller is composed of a monostable circuit and a constant-current charger (CCC). The controller use the primary-side feedback control strategy to eliminate the thermometer effect occurring in the cold-cathode fluorescent lamp (CCFL).The referred sawtooth is composed with a constant-period charge time and a variable dead-time. The synchronizing strategy is conducted by modulating the dead-time according to the resonant frequency of the Royer inverter. The design strategy for building the design example is proposed. A DTM-PWM controlled dimmable Royer inverter with two-CCFL by primary-side control is realized and experimented. The results of analysis and theoretical prediction are verified with experiments.