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Control of open-end induction motor by multi-objective GA based selective harmonic elimination PWM to reduce zero sequence currents and torque ripples

Kumar K. Kalyan, Anuradha K., Suryakalvathi M.

Journal of Power Technologies

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2023

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Vol. 103, nr 1

72--87

EN

A double inverter powered induction motor with open stator winding has few benefits, including excessive error forbearance functionality, great flexibility and lesser rating of DC input voltage etc. For this Configuration, two types of Modules can be implemented: they are Non-Isolated DC link and Isolated DC link. In these two, Non-Isolated DC link is a good choice due to effective DC-link utilization and ruggedness, which is very beneficial in many applications. However, this module produces more zero sequence currents (Z-SC) by means of common mode (CMMD) voltage, which flows through DC bus. The circulation of Z-SC must be as little as possible since it merely rises the amplitude of currents in all phases. High ripple frequency of currents and torque, in addition results in extra loss, which not only reduces the efficiency, but influences loading ability and quickens the aging of drive. The Triplen harmonics can be defined as harmonics with integer of three times the frequency at fundamental, when they are in Phase in all Phases forms the Z-SC. In this paper, a novel SHE method is chosen to target Triplen harmonics in Single DC Source Module (Non- Isolated) and holding preferred fundamental quantity, which aids in improving the torque handling ability of the motor. In addition, the investigation of dual inverter fed OEW-IM with both common DC source as well as separate DC sources is also explored in the SHE for different number of switching angles and variable Modulation Index (MI) towards the torque ripples and Z-SC reduction given. The foremost challenge related to the SHE method is resolving a set of higher order nonlinear equations with a number of variables. A Multi-objective GA method is provided for that challenge which effects the reduction in Z-SC so that torque ripples will be minimized. Moreover, the novel SHE method reduces the number of harmonics better than the conventional SHE, which further decreases TH-D with decent fundamental quantity. For validation, the essential mathematical formulations and simulation results are presented.

2

Minimization of torque ripple in induction motor drive by optimal harmonic elimination

Pratap C. Benin, Selvakumar A. Immanuel, Sathiyan S. Paul, Let G Shine

Przegląd Elektrotechniczny

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2022

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R. 98, nr 4

36--39

EN

Cascaded H-Bridge Multilevel Inverter (CH-MLI) is rich in output voltage harmonics. If MLI’s poly-phase output voltage is fed directly as input to drive an induction motor, there is great change in the performance of the motor output. To reduce the lower order harmonics in CH-MLI, a novel selective harmonic elimination method is proposed in this paper. The proposed Cross-Entropy (CE) optimization is implemented to find the optimal switching angle of CH-MLI. The switching angles determined are generated by sinusoidal pulse width modulation in MATLAB based simulation. The performance of CE optimized 11-level CH-MLI connected to an induction motor drive is compared with existing optimization methods. The torque ripple and total harmonics distortion (THD) comparisons are studied. Moreover, Cross-Entropy optimization algorithm simulation results are found superior to the other algorithms in reducing the THD as well as a reduced torque ripple. Using CE optimization technique about 14.45% reduction in torque ripple is attained and 19.14% reduction in THD is found.

PL

Kaskadowy wielopoziomowy falownik H-Bridge (CH-MLI) jest bogaty w harmoniczne napięcia wyjściowego. Jeśli wielofazowe napięcie wyjściowe MLI jest podawane bezpośrednio jako wejście do napędzania silnika indukcyjnego, następuje duża zmiana w wydajności mocy wyjściowej silnika. Aby zredukować harmoniczne niższego rzędu w CH-MLI, w niniejszym artykule zaproponowano nową metodę selektywnej eliminacji harmonicznych. Proponowana optymalizacja entropii krzyżowej (CE) jest wdrażana w celu znalezienia optymalnego kąta przełączania CHMLI. Wyznaczone kąty przełączania są generowane przez sinusoidalną modulację szerokości impulsu w symulacji opartej na MATLAB. Wydajność 11-poziomowego CH-MLI zoptymalizowanego pod kątem CE, podłączonego do napędu silnika indukcyjnego, jest porównywana z istniejącymi metodami optymalizacji. Badane są porównania tętnienia momentu obrotowego i całkowitego zniekształcenia harmonicznego (THD). Co więcej, wyniki symulacji algorytmu optymalizacji krzyżowej entropii okazały się lepsze od innych algorytmów pod względem redukcji THD, a także zmniejszonego tętnienia momentu obrotowego. Przy użyciu techniki optymalizacji CE osiągnięto około 14,45% zmniejszenie tętnienia momentu obrotowego i 19,14% zmniejszenie THD.

3

Mathematical modeling and engineering design of multi-level inverter based on selective harmonic elimination

Salman Layth S., Al-Badrani Harith

Przegląd Elektrotechniczny

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2022

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R. 98, nr 11

83--86

EN

SHE is a well-studied alternative to common PWM methods. This work shows how to use a Newton Raphson method to selectively reduce higher or lower order harmonics while preserving the needed fundamental voltage in asymmetrical multilevel inverter. This strategy can be used with any number of levels in asymmetrical multilevel inverter. For example, a 9-level and 27-level asymmetrical multilevel inverter is analyzed in this research, and the optimal angles are determined to eliminate the 3rd, 5th and 7th harmonics for nine level inverter and to eliminate twelve odd harmonic from 3rd harmonic to 25th harmonic for twenty seven level inverter.

PL

SHE jest dobrze zbadaną alternatywą dla popularnych metod PWM. Ta praca pokazuje, jak wykorzystać metodę Newtona Raphsona do selektywnej redukcji wyższych lub niższych harmonicznych przy jednoczesnym zachowaniu wymaganego napięcia podstawowego w asymetrycznym falowniku wielopoziomowym. Ta strategia może być stosowana z dowolną liczbą poziomów w asymetrycznym falowniku wielopoziomowym. Na przykład w tych badaniach analizowany jest 9-poziomowy i 27-poziomowy asymetryczny wielopoziomowy falownik, a optymalne kąty są określane w celu wyeliminowania 3, 5 i 7 harmonicznej dla 9-poziomowego falownika oraz wyeliminowania 12 nieparzystych harmonicznych od 3 do 25 harmonicznej. harmonicznych dla dwudziestu siedmiu poziomów falownika.

4

WTHD minimisation in hybrid multilevel inverter using biogeographical based optimisation

Kavitha R., Thottungal R.

Archives of Electrical Engineering

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2014

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Vol. 63, nr 2

187--196

EN

Harmonic minimisation in hybrid cascaded multilevel inverter involves complex nonlinear transcendental equation with multiple solutions. Hybrid cascaded multilevel can be implemented using reduced switch count when compared to traditional cascaded multilevel inverter topology. In this paper Biogeographical Based Optimisation (BBO) technique is applied to Hybrid multilevel inverter to determine the optimum switching angles with weighted total harmonic distortion (WTHD) as the objective function. Optimisation based on WTHD combines the advantage of both OMTHD (Optimal Minimisation of Total Harmonic Distortion) and SHE (Selective Harmonic Elimination) PWM. WTHD optimisation has the benefit of eliminating the specific lower order harmonics as in SHEPWM and minimisation of THD as in OMTHD. The simulation and experimental results for a 7 level multilevel inverter were presented. The results indicate that WTHD optimization provides both elimination of lower order harmonics and minimisation of Total Harmonic Distortion when compared to conventional OMTHD and SHE PWM. Experimental prototype of a seven level hybrid cascaded multilevel inverter is implemented to verify the simulation results.