Performance improvement of induction motor by Selective Harmonic Elimination (SHE) using Newton Raphson (N-R) method

Abstract

The paper presents an induction motor model with improvised performance by unified approach for selective Harmonic Elimination (SHE) of 3-Phase Voltage Source Inverter (VSI). Due to switching in inverters harmonics are present, the performance of inverter can be improved by reducing the harmonics. At this stage of time where everyone focus on increasing the level of inverter, lose their attention towards harmonic reduction. AS we know several modulation methods have been implemented to multilevel inverters. The modulation methods with higher switching frequency reduce filter size but increases switching losses. The Step modulation method operates with low switching frequency has less switching losses but the required filter size is large. To reduce the filter size the number of levels of the inverter has to be increased but it increases the cost of the system. This paper presents a novel modulation method where additional notches are introduced in the multi-level output voltage. The projected work investigates the Selective Harmonics Elimination (SHE) to eliminate harmonics produced by Pulse Width Modulation (PWM) [1] inverter. The model presented here eliminate the even order harmonics due to the symmetry of the wave, 3rd and multiple of 3rd order harmonics are eliminated due to fact that the harmonics wave of all 3 phases are in space phase, but differ in time phase by 120 degree, along with this 5th and 7th harmonics are eradicated by using SHE technique. The proposed modulation method is verified through MATLAB Simulink simulation.