Journal articles: 'Switching Angles'

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Brijesh, Rajput*1 &. Dr. RudraPratapsingh chauhan2. "A REVIEW ARTICLEOF THREE PHASE PSO BASED HARMONICS REDUCTION TECHNIQUE." INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY 7, no. 4 (2018): 375–81. https://doi.org/10.5281/zenodo.1218615.

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This paper reports particle swarm optimization (PSO) technique for selective harmonic elimination (SHE) in pulse width modulated inverter. A PSO based optimization technique is proposed to minimize the overall THD of the output voltage of PWM inverter and corresponding switching angles are computed. This method is applied for the bipolar switching in three phase inverter for three switching angles and five switching angles. The switching angles are computed to completely eliminate the lower order harmonics. The result of the bipolar case using three switching angles are compared with that of a recently reported work, based on PSO technique, And is observed that the proposed method is effective in eliminating the lower order harmonics completely and overall THD is reducing to a greater extent than the previously reported work.

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Hiendro, Ayong, Ismail Yusuf, Junaidi Junaidi, Trias Pontia Wigyarianto, and Yohannes M. Simanjuntak. "Optimization of SHEPWM cascaded multilevel inverter switching patterns." International Journal of Power Electronics and Drive Systems (IJPEDS) 11, no. 3 (2020): 1570. http://dx.doi.org/10.11591/ijpeds.v11.i3.pp1570-1578.

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Selective harmonic elimination (SHE) is an efficient method to eliminate low-order selected harmonics. However, due to nonlinearity in the problems, many optimization techniques give unsatisfied performances in finding optimum switching angles for the SHE. This paper proposes a modified moth-flame optimization algorithm to eliminate selective harmonics in cascaded multilevel inverters. The optimization algorithm is employed to find sets of optimum switching angles for cascaded 5-level, 7-level, and 9-level inverters. The results have shown that modified moth-flame optimization is beneficial in finding optimum switching angles. It performs better than moth-flame optimization (MFO) and differential evolution (DE) algorithms. The optimum switching angles are applied to generate switching pulses for a cascaded 9-level inverter to demonstrate the algorithm’s accuracy. As a result, the low-order harmonics are entirely removed from the ac output voltage of the inverter.

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Wong, Quan Ming, Yee Wei Sea, Wei Tik Chew, et al. "Determination of minimal total harmonic distortion for single-phase multilevel inverter." International Journal of Power Electronics and Drive Systems (IJPEDS) 15, no. 3 (2024): 1662. http://dx.doi.org/10.11591/ijpeds.v15.i3.pp1662-1670.

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Multilevel inverters (MLIs) offer numerous advantages, such as low voltage stresses on power switches, low switching losses, and high efficiency. Switching angles applied to MLI must be selected carefully to generate an output voltage waveform with low total harmonic distortion (THD). This paper proposes an improved algorithm to determine the switching angles with low THD for MLI. The proposed algorithm has been implemented using a MATLAB script to compute a set of switching angles with low THD from 3- to 31-level cascaded H-bridge MLI (CHBMLI). A PSIM simulation model has been developed to validate the switching angles and the corresponding THDs obtained from the MATLAB script. An experimental prototype has also been developed to validate the simulation results. The results obtained from the MATLAB script, the PSIM simulation, and the experimental measurement are in good agreement.

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Wong, Quan Ming, Yee Wei Sea, Wei Tik Chew, et al. "Determination of minimal total harmonic distortion for single-phase multilevel inverter." International Journal of Power Electronics and Drive Systems (IJPEDS) 15, no. 3 (2024): 1662–70. https://doi.org/10.11591/ijpeds.v15.i3.pp1662-1670.

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Multilevel inverters (MLIs) offer numerous advantages, such as low voltage stresses on power switches, low switching losses, and high efficiency. Switching angles applied to MLI must be selected carefully to generate an output voltage waveform with low total harmonic distortion (THD). This paper proposes an improved algorithm to determine the switching angles with low THD for MLI. The proposed algorithm has been implemented using a MATLAB script to compute a set of switching angles with low THD from 3- to 31-level cascaded H-bridge MLI (CHBMLI). A PSIM simulation model has been developed to validate the switching angles and the corresponding THDs obtained from the MATLAB script. An experimental prototype has also been developed to validate the simulation results. The results obtained from the MATLAB script, the PSIM simulation, and the experimental measurement are in good agreement.

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Ayong, Hiendro, Yusuf Ismail, Junaidi, Trias Pontia Wigyarianto F., and M. Simanjuntak Yohannes. "Optimization of SHEPWM cascaded multilevel inverter switching patterns." International Journal of Power Electronics and Drive System (IJPEDS) 11, no. 3 (2020): 1570–78. https://doi.org/10.11591/ijpeds.v11.i3.pp1570-1578.

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Selective harmonic elimination (SHE) is an efficient method to eliminate low-order selected harmonics. However, due to nonlinearity in the problems, many optimization techniques give unsatisfied performances in finding optimum switching angles for the SHE. This paper proposes a modified moth-flame optimization algorithm to eliminate selective harmonics in cascaded multilevel inverters. The optimization algorithm is employed to find sets of optimum switching angles for cascaded 5-level, 7-level, and 9-level inverters. The results have shown that modified moth-flame optimization is beneficial in finding optimum switching angles. It performs better than moth-flame optimization (MFO) and differential evolution (DE) algorithms. The optimum switching angles are applied to generate switching pulses for a cascaded 9-level inverter to demonstrate the algorithm’s accuracy. As a result, the low-order harmonics are entirely removed from the ac output voltage of the inverter.

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Kavitha, R., Rani Thottungal, and Brindha R. "Harmonic Elimination of Seven Level Inverter with Switching Pattern Reconfiguration Technique Using Hybrid BBO/MAS Algorithm." International Journal of Applied Power Engineering (IJAPE) 5, no. 2 (2016): 79. http://dx.doi.org/10.11591/ijape.v5.i2.pp79-86.

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A hybrid optimization algorithm is proposed in this paper to find the optimum switching angles in a Cascaded Multilevel Inverter (CMLI). A seven level cascaded inverter is considered and optimum switching angles are found by hybrid Biogeographical Based Optimization search (BBO) / Mesh Adaptive Direct Search (MAS) algorithm. The fundamental frequency Selective Harmonic Elimination-Pulse Width Modulation (SHE-PWM) technique is applied in order to reduce the switching losses.Reconfiguration technique is also proposed to achieve harmonic elimination for entire Modulation index(M). The various performance indices like phase THD, line THD, lower order harmonics eliminated in a CMLI are calculated based on the optimized switching angles. A seven level CMLI is simulated in MATLAB/SIMULINK by using switching angles calculated from BBO/MAS algorithm and the FFT analysis of traditional SHE-PWM and reconfiguration SHE-PWM methods are compared and verified with the calculated values from BBO/MAS algorithm.

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Soo, J. A., M. S. Chye, Y. C. Tan, S. L. Ong, J. H. Leong, and T. Sutikno. "Non-iterative Wide-modulation-index Switching-angle Calculation Techniques for 15-level Binary Cascaded H-bridge Multilevel Inverter." International Journal of Power Electronics and Drive Systems (IJPEDS) 8, no. 1 (2017): 93. http://dx.doi.org/10.11591/ijpeds.v8.i1.pp93-99.

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Cascaded H-bridge multilevel inverter (CHBMI) is able to generate a staircase AC output voltage with low switching losses. The switching angles applied to the CHBMI have to be calculated and arranged properly in order to minimize the total harmonic distortion (THD) of the output voltage waveform. In this paper, two non-iterative switching-angle calculation techniques applied for a 15-level binary asymmetric CHBMI are proposed. Both techniques employ a geometric approach to estimate the switching angles, and therefore, the generated equations can be solved directly without iterations, which are usually time-consuming and challenging to be implemented in real-time. Apart from this, both techniques are also able to calculate the switching angles for a wide range of modulation index. The proposed calculation techniques have been validated via MATLAB simulation and experiment.

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Mansoor, Abdal K., Laith A. Mohammed, and Noha A. AL Jawady. "Eliminating Harmonics in a Five Level Inverter by Optimized Both Switching Angles and Dc Link Voltage." Tikrit Journal of Engineering Sciences 15, no. 4 (2008): 1–13. http://dx.doi.org/10.25130/tjes.15.4.01.

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This paper presents design and analysis of a single phase multilevel inverter by optimizing both switching angles and DC link voltage of a cascaded inverter. The switching angles and dc link voltage are chosen such that to minimize the total harmonic distortion of the output voltage. The main power devices are switched only once per cycle , so that to overcome the switching loss problem, as well as electromagnetic interference (EMI) problem, a method is given to determine the optimum value of the switching angles and the value of the dc link voltage. Theoretical analysis and simulation of a single phase 5-level cascaded inverter are introduced with a wide range of modulation index.

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Jubair Al-Hiealy, Mohammed Rasheed, Mohammad Shahir Bin Abdul Majed Shikh, Abdurrahman Bin Jalil, Suhaila Abdul Rahman, and Muath Jarrah. "Management switching angles real-time prediction by artificial neural network." Indonesian Journal of Electrical Engineering and Computer Science 23, no. 1 (2021): 110. http://dx.doi.org/10.11591/ijeecs.v23.i1.pp110-119.

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Artificial neural networks (ANNs) is an efficient way for different types of real-world prediction problems. In the past decade, it has given a tremendous surge in a global research activities. ANNs embody much certainty and provide a great deal of promise This paper has present artificial neural network (ANN) technique analysis and prediction for management switching angles real-time. The proposes to be used ANN for prediction and selected obtine angles for implement the timing diagram for mulitlvel inverter circuit. In order to control the fundamental component, ANNs are used to solve the analysis of non-linear equation of the output timing diagram in order to determine the switching angles. Substantially, the number of switching devices are reducing as possible basically for reducing a switching loss in the system, also have been used ANNs technique to optimize a switching angles behavior to reduce total harmonic distortion (THD) at voltage and current output waveform equal THDV 8.05% THDA 5.1%. For the proposed controllers, the performance and results by the ANNs were obtained and compared by using MATLAB software.

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Al-Hiealy, Mohammed Rasheed Jubair, Mohammad Shahir, Abdurrahman Abdurrahman, Suhaila Abdul Rahman, and Muath Jarrah. "Management switching angles real-time prediction by artificial neural network." Indonesian Journal of Electrical Engineering and Computer Science 23, no. 1 (2021): 110–19. https://doi.org/10.11591/ijeecs.v23.i1.pp110-119.

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Artificial neural networks (ANNs) is an efficient way for different types of real-world prediction problems. In the past decade, it has given a tremendous surge in a global research activities. ANNs embody much certainty and provide a great deal of promise This paper has present artificial neural network (ANN) technique analysis and prediction for management switching angles real-time. The proposes to be used ANN for prediction and selected obtine angles for implement the timing diagram for mulitlvel inverter circuit. In order to control the fundamental component, ANNs are used to solve the analysis of non-linear equation of the output timing diagram in order to determine the switching angles. Substantially, the number of switching devices are reducing as possible basically for reducing a switching loss in the system, also have been used ANNs technique to optimize a switching angles behavior to reduce total harmonic distortion (THD) at voltage and current output waveform equal THDV 8.05% THDA 5.1%. For the proposed controllers, the performance and results by the ANNs were obtained and compared by using MATLAB software.

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Hamed, Hany A., Fatima N. Al Mansoori, and Ehab Bayoumi. "A new approach to enhance the accuracy of selective harmonics-elimination technique for digital controllers." Journal of Electrical Engineering 70, no. 5 (2019): 358–69. http://dx.doi.org/10.2478/jee-2019-0067.

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Abstract The selective harmonic elimination (SHE) is a preferable modulation technique in medium and high power converters applications as it enables for using low switching frequency with high flexibility to eliminate specific harmonics. The digital implementation of the SHE is a challenging issue as it requires a very accurate generation of the switching pulses. The theoretical calculation of the switching angles cannot guarantee the same results when digitally implemented by digital controllers. The digitizing process with a relatively low sampling frequency due to the digital implementation introduces error for each applied switching angle. Consequently, the applied switching angles will not match the theoretical ones resulted in residual errors for the selected harmonics that should be eliminated. This paper presents a new approach to improve SHE accuracy by online prediction and implementing of the closest true angles to minimize the residual harmonics.

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Mohamad, Bashar S., Taha A. Hussein, and Laith A. Mohammed. "Design and Implementation of a Cpld-Based Multilevel Inverter Depending on a Complex Programmable Logic Device (CPLD)." Tikrit Journal of Engineering Sciences 16, no. 4 (2009): 12–19. http://dx.doi.org/10.25130/tjes.16.4.02.

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A complex programmable logic device (CPLD) based multilevel inverter has been designed and implemented. The design involves three main parts. The first part is the switching angle generator (SAG), which determines the switching angles from an optimized primitive angle. The second part is the switching pulse generator (SPG), which controls the drive circuit of the inverter. The timing circuit is the third part, which provides the necessary timing for both SAG and SPG. Implementing both SAG and SPG using a CPLD device mean high speed cycle time. Hence an accurate timing for the switching angles is obtained compared to other procedures that uses software for calculating and generating the switching angles, such as microcontroller. MATLAB work space has been used to acquire and analyze the inverter output via the PC sound card. Results of the implemented inverter staircase output voltage, as well as the output frequency spectrum are obtained.

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Zawawi, M. N. M., Z. M. Isa, M. H. Arshad, B. Ismail, and M. H. N. Talib. "Comparative Study of Multiphase 5-Level Cascaded H-Bridge Multilevel Inverter System." Journal of Physics: Conference Series 2312, no. 1 (2022): 012062. http://dx.doi.org/10.1088/1742-6596/2312/1/012062.

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Abstract In terms of cost and structural design, the cascaded H-bridge multilevel inverter (CHBMLI) has a significant advantage over diode clamped and capacitor clamped multilevel inverters. The total harmonic distortion (THD) of a 5-level CHBMLI system for three different phases (single-phase, three-phase, and six-phase system) is studied and compared in this work. As switching angles play a role in lowering THD, the switching angles for a 5-level CHBMLI are evaluated using four specific switching angle methods in the initial section of this paper. In the simulation of single-phase system, these angles are being utilized. The angles with the lowest THD value are chosen for three-phase and six-phase system simulation. Based on the findings, the higher phase of 5-level CHBMLI is more efficient in decreasing harmonics.

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Chitrakala, G., N. Stalin, and V. Mohan. "Normally Bypassed Cascaded Sources Multilevel Inverter with RGA Optimization for Reduced Output Distortion and Formulaic Passive Filter Design." Journal of Circuits, Systems and Computers 29, no. 02 (2019): 2050019. http://dx.doi.org/10.1142/s021812662050019x.

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The distributed generation involving multiple photovoltaic sources and synthesizing high-quality ac voltage from those multiple dc sources are nascent research ambits. A host of multilevel inverters (MLIs) has been ascertained for performing above errand diligently, where the component count is obnoxious. The single phase seven-level inverter is an acquiescent compromise between the circuit complexity and the quality of the output. Further enhancement on the performance can be succored through optimizing dc link voltages and switching angles. This paper proposes a component count pruned MLI structure and also a refined genetic algorithm (RGA)-based optimization scheme for the computation of both dc link voltages and switching angles. Previous attempts for this problem have solved the switching angles with the objective of resulting minimum harmonic content in the staircase-shaped output voltage. The dc link voltage of each level is however assumed to be the same and constant. As an extension, RGA-based optimization of both dc link voltages and switching angles is triumphed. The harmonic profile of the proposed switching strategy is simulated and also corroborated by a hardware prototype. In practice, the proposed fundamental switched strategy is apposite, in which each dc voltage can be self-maintained and independently controlled. In addition, a method for designing the passive LC filter is also presented.

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Mohammed, Laith A., Taha A. Husain, and Ahmed M. T. Ibraheem. "Implementation of SHE-PWM technique for single-phase inverter based on Arduino." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 4 (2021): 2907. http://dx.doi.org/10.11591/ijece.v11i4.pp2907-2915.

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This paper presents design and practical implementation of single-phase inverter based on selective harmonic elimination-pulse width modulation (SHE-PWM) technique. Microcontroller mega type Arduino used as a controller for producing the gate pulses. The optimized switching angles determination results in wide range of output voltage. Depending on number of switching angles, the lower order harmonics (LOHs) can be eliminated to improve the output voltage waveform. A comparison study using MATLAB/Simulink for sinusoidal-PWM and SHE-PWM techniques, which shows for the same LOH in the output voltage waveform, the SHE-PWM has less number of pulses per half cycle than sinusoidal-PWM strategy. The reduction in number of pulses results less switching losses. The simulation done using ten switching angles to drive R-L load. A prototype of SHE-PWM inverter with R-L load is used to validate the simulation results.

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Laith, A. Mohammed, A. Husain Taha, and M. T. Ibraheem Ahmed. "Implementation of SHE-PWM technique for single-phase inverter based on Arduino." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 4 (2021): 2907–15. https://doi.org/10.11591/ijece.v11i4.pp2907-2915.

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This paper presents design and practical implementation of single-phase inverter based on selective harmonic elimination-pulse width modulation (SHE-PWM) technique. Microcontroller mega type Arduino used as a controller for producing the gate pulses. The optimized switching angles determination results in wide range of output voltage. Depending on number of switching angles, the lower order harmonics (LOHs) can be eliminated to improve the output voltage waveform. A comparison study using MATLAB/Simulink for sinusoidal-PWM and SHE-PWM techniques, which shows for the same LOH in the output voltage waveform, the SHE-PWM has less number of pulses per half cycle than sinusoidal-PWM strategy. The reduction in number of pulses results less switching losses. The simulation done using ten switching angles to drive R-L load. A prototype of SHEPWM inverter with R-L load is used to validate the simulation results.

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Hatef, Firouzkouhi. "FPGA Based Implementation of Cascaded Multi-level Inverter with Adjustable DC." International Journal of Research and Engineering 5, no. 7 (2018): 450–56. https://doi.org/10.21276/ijre.2018.5.7.3.

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In this paper, total harmonic distortion (THD) minimization problem for cascaded H-Bridge multilevel inverters (CHB-MLIs) with unequal DC sources is studied, which the DC voltage levels of CHB-MLI is considered to be dependent on switching angles. Two forms of variations are proposed for DC voltage, considering corresponding switching angles. A simplified THD formulation, independent from the DC voltage is presented. Both Homotopy method and Genetic Algorithm is applied for THD minimization using Selective Harmonic Elimination PWM (SHEPWM). The results show less THD results using GA. The simulation results are demonstrated by experiments on a seven-level inverter controlled by Xilinx SPARTAN3 FPGA (XC3S400-PQG208). The results show that switching angles for minimum THD can be considered constant for desired fundamental voltages.

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Osama Y. AL-Rawi. "SWITCHING ANGLE OPTIMIZATION BASED GENETIC ALGORITHMS FOR HARMONIC REDUCTION IN THREE-PHASE PWM STRATEGY." Diyala Journal of Engineering Sciences 4, no. 1 (2011): 83–94. http://dx.doi.org/10.24237/djes.2011.04106.

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In variable speed drive (VSD), it is desirable to reduce the harmonic effects, which causes current distortion and torque pulsation, besides, the harmonic power losses is an additional power losses that is introduced in the motor due to the presence of harmonic voltages. However, the problem of the high total harmonic current distortion (THD) still exists specially at low and medium speeds by using sub-optimal pulse width modulation (PWM) strategy. In the past to generate optimized PWM, is done by defining a general PWM in terms of a set of switching angles. Which result in a set of nonlinear equations in terms of the unknown switching angles. These equations are nonlinear as well as transcendental in nature. There is no efficient method that can be applied to solve such equations. The practical method of solving these equations is a trial and error process. Taking all the factors into account, a numerical technique can be applied to solve these set of nonlinear equations, but with some limitations. To overcome these limitations, Genetic algorithms (GAs) serves to search for optimal switching angles setting. In addition, the (THD) will be reduced, this lead to obtain the optimal PWM waveform and to simplify the practical implementation, and then improving the performance of the system output. GAs were employed as a search and optimization engine. Normally the tuning of the switching angles is a trail and error problem. In this paper, GAs provides a much simpler approach to off-line tuning of PWM switching angles than the rather complicated non-genetic optimization algorithms

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Sánchez Vargas, Oscar, Susana Estefany De León Aldaco, Jesús Aguayo Alquicira, Luis Gerardo Vela Valdés, and Jesús Darío Mina Antonio. "Differential Evolution Applied to a Multilevel Inverter—A Case Study." Applied Sciences 12, no. 19 (2022): 9910. http://dx.doi.org/10.3390/app12199910.

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This work aims to obtain the switching angles to reduce the total harmonic distortion (THD) and compare the different sets of angles obtained by modifying the modular index (Mi) in a seven-level multilevel inverter using the differential evolution (DE) algorithm. A seven-level cascaded multilevel inverter with RL load was simulated in MATLAB Simulink. The Mi was varied (0.6 to 1.27) to check which set of switching angles is optimal to reduce the THD. These sets of angles are then experimentally validated on a test bench. A brief discussion of the results is presented, comparing the minimum THD found without considering Mi, versus the minimum THD obtained if Mi is less than 1.

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Mahendran, S., Gnanambal I, and Maheswari A. "Quality Enhancement of AC Chopper Using Genetic Algorithm." TELKOMNIKA Indonesian Journal of Electrical Engineering 16, no. 1 (2015): 30. http://dx.doi.org/10.11591/tijee.v16i1.1584.

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This paper mainly deals with the design of AC chopper using Genetic Algorithm based harmonic elimination technique. Genetic Algorithm is used to calculate optimum switching angles to eliminate lower order harmonics in the output voltage. Total Harmonic Distortion of output voltage is calculated from the obtained switching angles and also adopted in the proposed fitness function. Comparative analysis is made for the switching angles obtained by the Newton Raphson method and the proposed Genetic Algorithm. The analysis reveals that the proposed technique is on par with conventional method. Additionally, the Genetic Algorithm approach offers less computational burden, guaranteed global optima in most cases and faster convergence. The proposed method is simulated in Matlab/Simulink model and the results shows that the proposed method works with high effectiveness, accuracy and rapidity.

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Attia, Hussain. "Evaluation of Selective Harmonic Elimination Pulse Width Modulation Technique for Unipolar Single-Phase H-Bridge Inverter: Comparative Study." International Journal of Power Electronics and Drive Systems (IJPEDS) 9, no. 3 (2018): 1157. http://dx.doi.org/10.11591/ijpeds.v9.i3.pp1157-1165.

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<span style="color: black; font-family: 'Times New Roman',serif; font-size: 9pt; mso-fareast-font-family: 'Times New Roman'; mso-ansi-language: EN-US; mso-fareast-language: EN-US; mso-bidi-language: AR-SA; mso-bidi-font-style: italic;">In this paper, a detailed comparative study about evaluating the single phase inverter performance based on selective harmonic elimination pulse width modulation (SHE PWM) technique is presented. Set of nonlinear equations are derived, four groups of switching angles are calculated using the numerical iterative method of Newton-Raphson. These angles are representing the ideal solutions to eliminate the low order harmonics from inverter output voltage and load current. Inverter effectiveness is evaluated by comparing the performance based on SHE PWM and based on the conventional constant switching frequency PWM (CSF PWM) technique. Same parameters setting is selected with considering the constant switching frequency value for each case separately as equivalent to the number of switching angles. Moreover, different rated load powers are investigated to explain the merit of SHE PWM within high power applications. MATLAB / Simulink simulation results are clearly indicating the priority of the SHE PWM at all groups of calculated angles and at different load power as well.

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Li, Ke Jun, Jian Guo Zhao, Lin Niu, and Cheng Hui Zhang. "Research on Mode-Switching Control of Thyristor Controlled Series Capacitor." Key Engineering Materials 439-440 (June 2010): 325–30. http://dx.doi.org/10.4028/www.scientific.net/kem.439-440.325.

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The mode-switching control method of thyristor controlled series capacitor (TCSC) is of great importance to power system stability. It is very difficult, if not impossible, to realize mode-switching only by changing firing angles. Considering the impedance characteristics of TCSC, a set of mode-switching control methods is proposed. Simulation and experimental results show that the proposed switching method can make the switching process faster and possess better dynamic performance.

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Chandran, Udayakumar, Sathiyasekar Kumarasamy, Ravi Samikannu, Rajamani M. P. E., Vinoth Krishnamoorthy, and Srinivasan Murugesan. "Tournament Selected Glowworm Swarm Optimization Based Measurement of Selective Harmonic Elimination in Multilevel Inverter for Enhancing Output Voltage and Current." Mathematical Problems in Engineering 2022 (March 30, 2022): 1–11. http://dx.doi.org/10.1155/2022/5845249.

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In modern days Multi Level Inverters (MLIs) in the power industry receive a large interest. The MLIs with multilevel structures produces higher-power, higher-voltage inverters. Selective Harmonic Elimination (SHE) has become a popular one. It has been utilized widely studied during the past several decades for multilevel inverters as it has many merits like lesser switching losses and lesser Total Harmonic Distortion (THD). However, many researchers have failed to reduce the selective harmonic elimination time consumption and improve efficiency. A novel Tournament Selected Glowworm Swarm Optimization-Based Selective Harmonic Elimination (TSGWSO-SHE) approach is proposed in this paper for addressing these problems. The major aim of the TSGWSO-SHE approach is selecting optimal switching angles for removing the lower order harmonics. In the TSGWSO-SHE technique, initially, multilevel-inverters are created, and the modulation index is measured. Based on the modulation index, Switching Angles (SAs) are determined. Then several switching angles are initialized randomly. The objective function is determined for every switching angle. Using it detects and chooses the neighbouring switching angle with higher brightness by tournament selection and move to it. Lastly, the switching angle updates its position and finds the optimal switching angle. In this way, an optimal SA is selected during the process of selective harmonic eradication in MLI with higher efficiency and minimal time consumption. The efficiency of TSGWSO-SHE technique is simulated using parameters such as time of SHE, SHE efficiency and THD. Results prove that the proposed TSGWSO-SHE technique provides better SHE performance as compared to the existing studies. Experimental results demonstrate that the TSGWSO-SHE technique reduces the THD and SHE time by 46% and 33%, and the efficiency of selective harmonic elimination is increased by 13% compared to existing methods.

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Vikramaditya, N. S., and J. Kurian. "Effect of aft wall slope on cavity pressure oscillations in supersonic flows." Aeronautical Journal 113, no. 1143 (2009): 291–300. http://dx.doi.org/10.1017/s0001924000002967.

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Abstract An experimental study of supersonic flow over wall mounted cavities with different aft wall angles is carried out. Unsteady pressure measurements were made on the walls and floor of the cavity. Data analysis was performed on the experimental results using statistical methods. In the case of higher angled cavities, the presence of an upstream traveling acoustic wave could be confirmed. For lower angled cavities (60 degrees and less) where the acoustic wave could not be identified, the flow inside the cavity was more or less stable. Mode switching occurring in higher angled cavities was confirmed by spectrogram studies.

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Nikolaev, A. A., and I. G. Gilemov. "Development and research of improved PWM algorithm of an active rectifier with variable switching angle tables." Vestnik IGEU, no. 6 (December 28, 2020): 48–56. http://dx.doi.org/10.17588/2072-2672.2020.6.048-056.

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Modern electric drives of rolling mills are based on frequency converters with active rectifiers (AR). During operation, active rectifiers consume non-sinusoidal current, having a negative effect on the supply network. In order to improve the performance index of voltage quality, AR special algorithms of pulse-width modulation are used. Selective harmonic elimination (SHE) PWM algorithm has become widespread. However, application of SHE PWM algorithm does not always allow to optimize the operation of the AR under the conditions of changing parameters of the electro-technical complex under various operating modes. Therefore, a solution is needed to improve the electrical power quality index of plant networks with powerful frequency converter with AR. To carry out the research, a mathematical model of the frequency converter with active rectifiers was implemented with an improved PWM algorithm in the Matlab-Simulink environment based on the parameters of the main electric drive of the 2000 cold rolling mill “LPC-11” of PJSC “ММК”. The main assumption of the simulation model is that the inverter is represented as a current source. An improved algorithm with the ability to select tables of switching angles based on SHE PWM has been developed. The operation of the FC with AR with the proposed improved PWM algorithm with variable tables of switching angles has been investigated. A comparative analysis of the instantaneous values of AR voltages and currents when transferring to the tables with similar switching angles and significantly different ones has been made. It has been found that changing the tables of switching angles does not have a significant negative effect on the operation of the FC with AR. The proposed improved PWM algorithm can be used to improve the performance index of power quality in electrotechnical complexes with FC and AR by using optimal tables of switching angles in conditions of various modes of the power supply system. The adequacy of the simulation model has previously been confirmed by experimental data and previous studies.

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Kandil, Shaimaa A., A. A. Ali, Adel El Samahy, Sherif M. Wasfi, and O. P. Malik. "Harmonic Optimization in Voltage Source Inverter for PV Application using Heuristic Algorithms." International Journal of Emerging Electric Power Systems 17, no. 6 (2016): 671–82. http://dx.doi.org/10.1515/ijeeps-2016-0052.

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Abstract Selective Harmonic Elimination (SHE) technique is the fundamental switching frequency scheme that is used to eliminate specific order harmonics. Its application to minimize low order harmonics in a three level inverter is proposed in this paper. The modulation strategy used here is SHEPWM and the nonlinear equations, that characterize the low order harmonics, are solved using Harmony Search Algorithm (HSA) to obtain the optimal switching angles that minimize the required harmonics and maintain the fundamental at the desired value. Total Harmonic Distortion (THD) of the output voltage is minimized maintaining selected harmonics within allowable limits. A comparison has been drawn between HSA, Genetic Algorithm (GA) and Newton Raphson (NR) technique using MATLAB software to determine the effectiveness of getting optimized switching angles.

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Yusof, Mohd Aizuddin, Yee Chyan Tan, M. Othman, et al. "Comparison of Switching Angle Arrangement Techniques in Single-Phase Boost Multilevel Inverter for Low-THD Operation." Applied Mechanics and Materials 793 (September 2015): 167–71. http://dx.doi.org/10.4028/www.scientific.net/amm.793.167.

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Multilevel inverters are one of the preferred inverter choices for solar photovoltaic (PV) applications. While these inverters are capable of producing AC staircase output voltage waveform, the total harmonic distortion (THD) of the output voltage waveform can become worse if the switching angle of each voltage level is not carefully chosen. In this paper, four switching angle arrangement techniques are presented and the switching angles generated by these techniques are applied to a new single-phase boost multilevel (SPBM) inverter. The performance of 3-, 5-, 7-, 9-and 11-level SPBM inverter having four different sets of switching angles derived using the aforementioned techniques have been evaluated and compared using PSIM software. Simulation results show that one of the techniques is able to produce an output voltage waveform with the lowest THD, whilst the other generates an output voltage waveform with the highest fundamental voltage component.

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Tohtayong, Majdee, Sheroz Khan, Mashkuri Yaacob, et al. "The Combination of Newton-Raphson Method and Curve-Fitting Method for PWM-based Inverter." International Journal of Power Electronics and Drive Systems (IJPEDS) 8, no. 4 (2017): 1919. http://dx.doi.org/10.11591/ijpeds.v8.i4.pp1919-1931.

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This paper presents the combination of two different methods to perform the waveform analysis for PWM-operated inverter. The two techniques are Newton-Raphson method and Curve-Fitting as a PWM concept to operate PWM-based inverter, the proper solutions of switching angles can valuate the initial values by using the Newton-Raphson method with the wide-step calculation of modulation indices. The solutions are then compared using a curve in order to study the behavior. Then, the Curve-Fitting method is used to estimate the missing solutions between any points of wide-step calculation. This combination method can estimate the probable solutions that cannot be solved by Newton-Raphson method in a wide-ranging of the modulation index and reduce the calculation time. PWM-based inverter, which is obtained the switching angles by Newton-Raphson method and the combination of two different methods, is verified by the simulation results showing faster performance with improved Total Harmonic Distortion (THD) than both methods alone when compared the same values of switching angles.

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Abd Halim, Wahidah, and Nasrudin Abd Rahim. "Selective Harmonic Elimination Method for Cascaded H-Bridge Multilevel Inverter." Applied Mechanics and Materials 785 (August 2015): 122–26. http://dx.doi.org/10.4028/www.scientific.net/amm.785.122.

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This paper presents a selective harmonic elimination (SHE) modulation technique for cascaded H-bridge (CHB) multilevel inverter. The main advantage of the proposed SHE concept is its simple implementation to eliminate the specific order harmonics. The procedures used to achieve the appropriate switching angles are presented. The switching angles are offline computed using the Newton-Raphson method. The SHE scheme of the adopted inverter uses the relationship between the angles and a sinusoidal reference waveform through some combinational logic gates. Theoretical results are verified by the experimental work of a single-phase 7-level CHB inverter employing an Altera DE2 field-programmable gate array (FPGA). Results show the inverter producing an optimum stepped output voltage when selected low-order harmonics are eliminated and the voltage total harmonic distortion (THD) is improved.

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Natarajan, Suresh, and R. Samuel Rajesh. "Comparison Of Cascaded H-bridge Inverters for Harmonic Mitigation Considering Various Loads." International Journal of Power Electronics and Drive Systems (IJPEDS) 8, no. 1 (2017): 10. http://dx.doi.org/10.11591/ijpeds.v8.i1.pp10-19.

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This paper compares the reduction of harmonics in various level cascaded H-bridge inverters. The switching angles for the cascaded H-bridge inverter were calculated by evolutionary optimization technique. Fourier analysis is used to determine the switching angles for the desired electrical parameters. Lower order harmonics such as third, fifth, seventh, ninth and eleventh order harmonics were taken into consideration to reduce the total harmonic distortion. Simulation was done for thirteen, fifteen and seventeen level cascaded H-bridge inverters using Matlab. Total harmonic distortion of voltage and current for R, RL and Motor load were analyzed.

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Wang, Libing, Chengxiong Mao, Dan Wang, Jiming Lu, Junfeng Zhang, and Xun Chen. "A Real-Time and Closed-Loop Control Algorithm for Cascaded Multilevel Inverter Based on Artificial Neural Network." Scientific World Journal 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/508163.

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In order to control the cascaded H-bridges (CHB) converter with staircase modulation strategy in a real-time manner, a real-time and closed-loop control algorithm based on artificial neural network (ANN) for three-phase CHB converter is proposed in this paper. It costs little computation time and memory. It has two steps. In the first step, hierarchical particle swarm optimizer with time-varying acceleration coefficient (HPSO-TVAC) algorithm is employed to minimize the total harmonic distortion (THD) and generate the optimal switching angles offline. In the second step, part of optimal switching angles are used to train an ANN and the well-designed ANN can generate optimal switching angles in a real-time manner. Compared with previous real-time algorithm, the proposed algorithm is suitable for a wider range of modulation index and results in a smaller THD and a lower calculation time. Furthermore, the well-designed ANN is embedded into a closed-loop control algorithm for CHB converter with variable direct voltage (DC) sources. Simulation results demonstrate that the proposed closed-loop control algorithm is able to quickly stabilize load voltage and minimize the line current’s THD (<5%) when subjecting the DC sources disturbance or load disturbance. In real design stage, a switching angle pulse generation scheme is proposed and experiment results verify its correctness.

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Aalami, H. A., and R. Salehi. "Extended Modulation Index with more Eliminated Low Order Harmonics at Cascaded Multilevel Inverters." Applied Mechanics and Materials 492 (January 2014): 123–27. http://dx.doi.org/10.4028/www.scientific.net/amm.492.123.

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Principle aim in standard Selective Harmonic Elimination pulse wide modulation (SHE-PWM) is elimination of low-order harmonics as well as production of desired fundamental component. To accomplish this objective, a set of N switching angles should be determined. In fact, N-1 angles are hired to remove N-1 harmonics from voltage waveform and one angle is allotted to produce the fundamental. This paper presents a solution in order to remove low order harmonics as much as possible. It suggests eliminating next harmonic instead of highest order harmonic in infeasible points. A genetic algorithm is employed to solve the new transcendental equation for finding the switching angles. The proposed method is experimentally applied to a seven-level cascaded H-bridge inverter. The results confirm the validity and effectiveness of the proposed method in extending modulation index range.

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Sea, Yee Wei, Wei Tik Chew, Siok Lan Ong, Quan Ming Wong, Ahmad Firdaus Ahmad Zaidi, and Jenn Hwai Leong. "Selected harmonic minimization in 3-phase 11-level switch-switch multilevel inverter using artificial gorilla troops optimization algorithm." Journal of Electrical Engineering 76, no. 2 (2025): 124–33. https://doi.org/10.2478/jee-2025-0013.

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Abstract A key challenge in designing 3-phase multilevel inverters (MLIs) is determining the switching angles that produce a low THD output voltage waveform. This work proposes an AGTO-SHMPWM technique for determining the switching angles, aiming to minimize low-order harmonics while achieving the desired fundamental harmonic. MATLAB analysis shows that the AGTO method achieves significantly lower objective function (OF) values, as low as 10– 32, compared to the GA and GOA methods. Cumulative distribution function analysis reveals that the AGTO method has a 38% probability of achieving an OF ≤ 10– 30, while the GA and GOA methods have a 0% probability. These results demonstrate that the AGTO method is more capable of thoroughly exploring the optimization solution space. PSIM simulation confirms that the switching angles computed using the AGTO method, when applied to a 3-phase 11-level switch-switch MLI (S2MLI), can produce sinusoidal-like staircase voltage waveforms with minimized V5, V7, V11 and V13 harmonics while achieving the desired fundamental voltage. The phase and line-to-line voltage THDs, when the S2MLI is operated at Midx of 0.80, are 7.93% and 5.55%, respectively, which are consistent with those predicted by MATLAB analysis.

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Chen, Jin Ping, Yong Feng Ju, and Yu Yao He. "Selective Harmonics Elimination for PWM Inverters Using the PSO Optimization Technique." Applied Mechanics and Materials 135-136 (October 2011): 879–85. http://dx.doi.org/10.4028/www.scientific.net/amm.135-136.879.

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Harmonic minimization in PWM inverters is a complex optimization problem which involves non-linear transcendental equations having multiple local minima. In this paper, a solution to the harmonic minimization problem using the particle swarm optimization (PSO) has been proposed to solve the SHE problem. It overcomes the complicated computations associated with conventional iterative techniques. As an example, in this paper a bipolar PWM inverter with seven switching angles per quarter cycle with varying modulation index is considered, and the optimum switching angles are calculated offline to eliminate the 5th,7th, 11th,13th,17th and 19th harmonics. The simulated results are also validated by experiment.

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Kameswari, Y. Lalitha, and O. Chandra Sekhar. "Fuzzy Logic Controlled Harmonic Suppressor in Cascaded Multilevel Inverter." International Journal of Power Electronics and Drive Systems (IJPEDS) 7, no. 2 (2016): 303. http://dx.doi.org/10.11591/ijpeds.v7.i2.pp303-310.

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This paper presents an investigation of seven level cascaded H-bridge (CHB) inverter in power system for compensation of harmonics.For power quality control a Fuzzy Logic Control (FLC) giving comparatively better harmonic reduction than the conventional controllers. Harmonic distortion is the most important power quality problem stirring in multilevel inverter, the harmonics can be eliminated by an optimal selection of switching angles. A hybrid evaluation technique evaluates the obtained optimal switching angles that are attained from the fuzzy inference system as well as neural network. The proposed method will be implemented in MATLAB working platform and the harmonic elimination performance will be evaluated.

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Al Quraan, Laith, Laszlo Szamel, and Mahmoud Hamouda. "Optimum Switching Angles Control of SRM for Electric Vehicle Applications." Periodica Polytechnica Electrical Engineering and Computer Science 65, no. 4 (2021): 394–403. http://dx.doi.org/10.3311/ppee.17640.

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Switched Reluctance Motor (SRM) drive is being gradually used in industrial applications, including electric vehicles (EVs), due to several advantages over conventional motors. However, the nonlinear magnetic characteristics of the motor make its controller very complicated. This paper presents a simplified procedure to obtain the optimal switching angles under hysteresis current control SRM drive over a wide range of speeds. A multi-objective optimization technique is applied to determine the optimal switch on and switch off angles that achieve the optimum combination of maximum average torque with minimum torque ripple and copper loss. A searching algorithm is developed for each operating point to define the maximum average torque and the minimum torque ripple and copper losses, as they vary for different currents and motor speeds. Then the optimal values of switching angles are stored in the lookup tables to build a MATLAB model of the SRM drive system. Finally, simulation and experimental results are presented to show the validity and effectiveness of the proposed controller.

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Sabirin, Nor Hidalina Mohd, Zainuddin Mat Isa, Mohd Hafiz Arshad, Baharuddin Ismail, Md Hairul Nizam Talib, and Ernie Che Mid. "Harmonics Elimination in 7-Level Multilevel Inverter Using Animal Migration Optimization Algorithm with Different Objective Functions." International Journal of Emerging Technology and Advanced Engineering 13, no. 1 (2023): 18–27. http://dx.doi.org/10.46338/ijetae0123_03.

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Harmonics can degrade the power quality of a multilevel inverter by causing the voltage to be distorted and vary from sinusoidal waveforms. Harmonics can be reduced by increasing the number of voltage levels or by employing suitable modulation techniques. In this paper, The Selective Harmonic Elimination Pulse Width Modulation (SHEPWM) modulation method is employed to obtain the optimal switching angles that able to reduce the specific individual harmonic and the Total Harmonic Distortion (THD) in singlephase 7-level Cascaded H-Bridge multilevel inverter. The Animal Migration Optimization (AMO) is proposed to acquire these angles using two difference objective functions. The performance is examined and evaluated. Both objective functions able to determine the optimal switching angles starting from modulation index of 0.34. However, the comparative study demonstratethat objective function number 2 has better performance in term of lowering selective individual harmonics as well as THD.

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Suresh, S., S. Kannan, and S. Ponnayira Sundaravel. "A Modified Single Phase H-Bridge Inverter for High Power Applications with Power Quality Improvement." Applied Mechanics and Materials 626 (August 2014): 118–26. http://dx.doi.org/10.4028/www.scientific.net/amm.626.118.

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Various multilevel inverter topologies are widely being used for real power exchange, reactive power compensation, harmonic current mitigation on grid and industrial drive applications with fundamental frequency switching mode of gate control. Still so many topologies are being currently developed with reduced number of switches, improved waveform for power quality improvement with fundamental frequency switching and pwm switching gate control mode. This paper presents the performance analysis of modified H-bridge single phase inverter for high voltage and high power applications. The switching method has been selected to operate the inverter at fundamental frequency switching mode of gate control to be free from lower order harmonics. The inverter has the modulation technique with pre calculated switching angles to generate the required fundamental voltage with reduced Total Harmonic Distortion (THD). So, the switching losses have been reduced hence the efficiency is improved with Power Quality (PQ) improvement in voltage-current waveform. The DC input power is feed to the inverter from DC capacitor voltage divider source, contributed to give various dc voltage levels during fundamental frequency switching of different switching combinations for the generation of stepping output voltage. During dynamic load condition, the magnitude of input dc voltage level across each capacitor has not undergone through big swing to feed the power to the load without affecting generated output ac voltage. The performance of the proposed inverter has been analyzed for dynamic reactive load and induction motor. The MATLAB based simulations have been presented to validate the inverter operation for dynamic reactive load and industrial drive applications with pre calculated THD reduced switching conduction angles for PQ improvement in waveform.

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Yusuf, Ismail, Ayong Hiendro, F. Trias Pontia Wigyarianto, and Kho Hie Khwee. "Differential Evolution Algorithm with Triangular Adaptive Control Parameter for SHEPWM Switching Pattern Optimization." International Journal of Power Electronics and Drive Systems (IJPEDS) 8, no. 3 (2017): 1381. http://dx.doi.org/10.11591/ijpeds.v8.i3.pp1381-1388.

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Differential evolution (DE) algorithm has been applied as a powerful tool to find optimum switching angles for selective harmonic elimination pulse width modulation (SHEPWM) inverters. However, the DE’s performace is very dependent on its control parameters. Conventional DE generally uses either trial and error mechanism or tuning technique to determine appropriate values of the control paramaters. The disadvantage of this process is that it is very time comsuming. In this paper, an adaptive control parameter is proposed in order to speed up the DE algorithm in optimizing SHEPWM switching angles precisely. The proposed adaptive control parameter is proven to enhance the convergence process of the DE algorithm without requiring initial guesses. The results for both negative and positive modulation index (M) also indicate that the proposed adaptive DE is superior to the conventional DE in generating SHEPWM switching patterns

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Voitovych, Yurii, Styslo Bohdan, Chmykhova Oksana, and Plakhtii Oleksandr. "RESEARCH OF COMMUTATION PROCESSES IN A 24-PULSE RECTIFIER WITH ELECTRONIC PHASE SHIFT ON IGBT TRANSISTORS WITH REVERSE BLOCKING CAPABILITY." Bulletin of the National Technical University «KhPI» Series: New solutions in modern technologies, no. 1(19) (April 26, 2024): 78–90. https://doi.org/10.20998/2413-4295.2024.01.11.

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When used in multi-pulse rectifiers with electronic phase shift, namely the use of single-operation semiconductor switches that can operate with lagging control angles and fully controlled semiconductor switches with reverse blocking capability that operate with leading control angles, the following feature occurs, namely that the switching time of single-operation keys and fully managed keys is different. The solution to this problem is possible when using fully controlled switches for all 6-pulse rectifiers, thereby unifying the converter modules. The disadvantage of such a solution is some increase in the cost of semiconductor elements. The scheme of unified modules can be performed on any fully controlled switches with reverse blocking capability, for example, symmetrical GTOs, or IGBTs with a series diode. When using fully controlled valves in rectifiers with an electronic phase shift, the switching of the valves occurs almost instantly, since the accumulated energy in the network cables cannot change instantly, this leads to the failure of the switches. To protect the keys, it is necessary to artificially create an additional switching circuit in the input circuit of the rectifier at the time of the current transition from one phase to another. The purpose of this article is to study the switching processes in a 24-pulse rectifier with an electronic phase shift on IGBT transistors with reverse blocking capability and the use of PWM to balance the average value of the rectified voltage of unified rectifiers operating with large and small control angles.

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Oloo, Jackson, and Szamel Laszlo. "Torque Ripple Minimization for Switched Reluctance Motor Drives Based on Harris Hawks–Radial Basis Function Approximation." Energies 18, no. 4 (2025): 1006. https://doi.org/10.3390/en18041006.

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Switched reluctance motor drives are becoming attractive for electric vehicle propulsion systems due to their simple and cheap construction. However, their operation is degraded by torque ripples due to the salient nature of the stator and rotor poles. There are several methods of mitigating torque ripples in switched reluctance motors (SRMs). Apart from changing the geometrical design of the motor, the less costly technique involves the development of an adaptive switching strategy. By selecting suitable turn-on and turn-off angles, torque ripples in SRMs can be significantly reduced. This work combines the benefits of Harris Hawks Optimization (HHO) and Radial Basis Functions (RBFs) to search and estimate optimal switching angles. An objective function is developed under constraints and the HHO is utilized to perform search stages for optimal switching angles that guarantee minimal torque ripples at every speed and current operating point. In this work, instead of storing the θon, θoff values in a look-up table, the values are passed on to an RBF model to learn the nonlinear relationship between the columns of data from the HHO and hence transform them into high-dimensional outputs. The values are used to train an enhanced neural network (NN) in an adaptive switching strategy to address the nonlinear magnetic characteristics of the SRM. The proposed method is implemented on a current chopping control-based SRM 8/6, 600 V model. Percentage torque ripples are used as the key performance index of the proposed method. A fuzzy logic switching angle compensation strategy is implemented in numerical simulations to validate the performance of the HHO-RBF method.

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Wu, Cheng-Yi, and Shiow-Kang Yen. "Domain Wall Injection in Spin Valve Systems with Reservoirs of Different Geometries." Crystals 10, no. 3 (2020): 187. http://dx.doi.org/10.3390/cryst10030187.

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This study investigates nanostrips in Co/Cu/Py spin valve structures by connecting one side to domain wall reservoirs of different shapes in order to manipulate the switching field. The switching field increases according to the injection geometry; a diamond-shape reservior generates the largest switching field, followed by square-shape and then tip shape reservoirs. Simulation indicated the same results, showing that the vortex domain walls nucleated at the junction, but the pinning force increased as the magnetic transition area became larger (the injection angle became smaller). Therefore, by controlling the domain wall injection angles, the switching fields of the nanostrips can be manipulated.

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Chaurasiya, Avinash, Manish Anand, and Rajdeep Singh Rawat. "Angle selective piezoelectric strain-controlled magnetization switching in artificial spin ice based multiferroic system." Journal of Applied Physics 131, no. 18 (2022): 183901. http://dx.doi.org/10.1063/5.0089902.

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The prospect of electrically controlled writing of ferromagnetic bits is highly desirable for developing scalable and energy-efficient spintronics devices. In this direction, various efforts have been made to achieve electrically controlled magnetization switching utilizing an artificial multiferroic system. To date, the magnetization switching has been realized in a diverse nanopatterned magnetic system. However, the demonstration of electric field-induced strain-controlled magnetization switching in artificial spin ice (ASI) coupled with a piezoelectric material is still unexplored. In the present work, we perform micromagnetic simulations to investigate the electric field-induced strain-mediated magnetization switching in an ASI based multiferroic system. Here, the piezoelectric strain-controlled magnetization switching has been studied by applying the electric-field pulse at different angles with respect to the axes of the system. Remarkably, magnetization switches by [Formula: see text] only if the external electric-field pulse is applied at some specific angles, close to the anisotropy axis of the system ([Formula: see text]–[Formula: see text]). Our detailed analysis of the demagnetization energy variation reveals that the energy barrier becomes antisymmetric in such cases, facilitating complete magnetization reversal. Moreover, we have also proposed a possible magnetization reversal mechanism with two sequential electric-field pulses of a relatively smaller magnitude. We believe that the present work could pave the way for a future ASI-based multiferroic system for scalable magnetic field-free low power spintronics devices.

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Zhou, Hai Ying, Kai Liu, and Ming Jiang. "Research on Clamping Body of the Hydraulic Climbing System of Caliper Type." Advanced Materials Research 580 (October 2012): 240–43. http://dx.doi.org/10.4028/www.scientific.net/amr.580.240.

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To investigate the appropriate inclined angles, spacing between caliper and square steel satisfying the requirement of caliper switching mechanism and the appropriate tooth parameters, the relation of inclined angles of caliper and meshing force is analyzed. And the hardness parameters of caliper and square steel are also analyzed. The appropriate tooth parameters are determined based on hardness parameters of caliper and square steel and tooth parameters of caliper.

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Shawanti, Roy, Paramanik Sayan, and Sarker Krishna. "An approach to harmonic optimization for 25KVA auxiliary converter used in indian railway." i-manager’s Journal on Electronics Engineering 13, no. 4 (2023): 36. http://dx.doi.org/10.26634/jele.13.4.20155.

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As the Indian railway network expands, the demand for reliable and efficient power systems, especially auxiliary converters supporting various on-board systems, grows. By reducing power losses and fuel consumption, it is more crucial to design an energy-efficient and economic auxiliary converter for the railway system. This is partially accomplished by using a 25KVA auxiliary (Aux.) converter, which can accept input electrical energy from a 110V DC battery at Self-Generation (SG) coaches. Biogeography Based Optimization (BBO) method of harmonic elimination for a 25KVA converter is described in this study. The paper explores the 120-degree mode of conduction and compares the existing technique with a proposed 7-switching selective odd harmonic removal method. Results from Matlab simulations demonstrate the effectiveness of the BBO technique in reducing Total Harmonic Distortion (THD). The output voltage waveforms with and without BBO are compared, showcasing a significant improvement in harmonic suppression. The paper concludes by emphasizing the practical implementation of the optimized switching angles using an ATmega2560R3 microcontroller. The online application of stored switching angles on the microcontroller is calculated offline.

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Dhal, P. K., and C. Christober Asir Rajan. "Total Harmonic Reduction Using Switching Frequency in H-Bridge Cascaded Multilevel Inverter." Applied Mechanics and Materials 446-447 (November 2013): 869–75. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.869.

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This paper presents total harmonics elimination in H-bridge Multi-Level Inverter. The basic concept of this reduction is to eliminate harmonics in different level with an appropriate choice of switching angles. This paper employs Homotopy algorithm to solve the transcendental equations for finding the switching angles. This method solves the nonlinear transcendental equations. It is much simpler formulation without complex analytical calculations for any number of voltage levels. In this technique, it is not required transformer allows the use of a single dc power source (e.g., a battery or a fuel cell stack) with the remaining n − 1dc sources being capacitors, which is referred to as hybridcascaded H-bridge multilevel inverter (HCMLI). It has several informative Mat lab simulation results verify the validity and effectiveness of the proposed algorithm.

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Nageswara Rao, G., K. Chandra Sekhar, and P. Sangameswararaju. "An Effective Technique for Reducing Total Harmonics Distortion of Multilevel Inverter." Journal of Intelligent Systems 27, no. 3 (2018): 433–46. http://dx.doi.org/10.1515/jisys-2016-0210.

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Abstract In this paper, an adaptive neuro fuzzy interference system (ANFIS) is proposed for eliminating voltage harmonics present in the multilevel inverter. It is achieved by reducing the total harmonic distortion (THD) present in the multilevel inverter output voltage. Here, the voltage variation of the multilevel inverter is determined from the actual load voltage and the reference voltage. The voltage variations at different time intervals have been applied to the ANFIS. According to the voltage variations, the switching angles can be generated from the interference system. These switching angles can make the multilevel inverter output voltage with reduced THD. The proposed technique is implemented in the MATLAB/simulink working platform. The effectiveness of the proposed method is evaluated by the multilevel inverter output voltage without controller and with neuro fuzzy controller (NFC).

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Bektaş, Yasin, Hulusi Karaca, Taha A. Taha, and Hussein I. Zaynal. "Red deer algorithm-based selective harmonic elimination technique for multilevel inverters." Bulletin of Electrical Engineering and Informatics 12, no. 5 (2023): 2643–50. http://dx.doi.org/10.11591/eei.v12i5.5160.

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This paper proposed a red deer algorithm (RDA)-based selective harmonic elimination (SHE) method for multilevel inverters (MLIs). To eliminate the desired harmonic orders, the optimum switching angles of the MLI have been calculated using the proposed RDA. The calculated switching angles have been applied to the 3-phase cascaded H-bridged 11-level inverter. In addition, the performance of the proposed RDA method was compared with the results of methods such as the Newton-Raphson (NR) method, LSHADE/EpSin technique (LSHADE), whale optimization algorithm (WOA), and particle swarm optimization (PSO) used for the SHE problem in the literature. The results obtained prove that the proposed RDA optimization solves the SHE problems more effectively than other methods. It has also been observed that RDA produces good solutions in different modulation indexes.

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Luo, Chuanchuan, and Bo Guan. "Common-Mode Voltage Suppression of a Five-Level Converter Based on Multimode Characteristics of Selective Harmonic Elimination PWM." Electronics 13, no. 2 (2024): 408. http://dx.doi.org/10.3390/electronics13020408.

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The combination of five-level converters with selective harmonic elimination pulse-width modulation (SHEPWM) is a practical need in medium-voltage, high-power applications. However, how to suppress the common-mode voltage (CMV) in this case becomes a difficult problem. Although CMV suppression under high switching frequency (SF) modulations and three-level SHEPWM has been discussed in many studies, these methods are not applicable to five-level SHEPWM. This is partly because the zero-sequence voltage under SHEPWM is difficult to adjust and partly because the solution spaces of three- and five-level SHEPWM are completely different. Moreover, conventional CMV suppression in three-level SHEPWM must sacrifice the switching angles to control the zero-sequence voltage, which makes the equivalent SF increase. Therefore, in this article, we propose a novel CMV suppression method that effectively utilizes the multimode characteristics of five-level SHEPWM. Multimode characteristics refers to the output waveform containing different levels of jump patterns. Therefore, there are a large number of switching angle trajectories in five-level SHEPWM, which outputs the same fundamental voltage with different CMVs. The proposed method uses the special multimode characteristics to reduce the CMV without sacrificing the switching angles. Its effectiveness and feasibility are verified by experiments.

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Stöttner, Julia, Andreas Rauscher, and Christian Endisch. "Pareto optimization of multilevel inverter structures regarding the DC magnitude, switching frequency and switching angles." International Journal of Electrical Power & Energy Systems 142 (November 2022): 108259. http://dx.doi.org/10.1016/j.ijepes.2022.108259.

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Journal articles on the topic 'Switching Angles'

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