Performance evaluation of induction motor for unipolar and bipolar pulse width modulation techniques

Abstract

Inverter is an interface device between a dc source and ac loads which converts DC voltage to a variable voltage, variable frequency AC voltage. While converting, it introduces harmonics in the output of the system which results in additional heating of induction motors. Hence in order to diminish these harmonics, different techniques are introduced viz. external and internal control techniques in which the latter is more efficient. Out of the all proposed methods, the internal control of inverter which is also called as Pulse Width Modulation (PWM) can be achieved either using unipolar modulation technique or bipolar modulation technique. In this paper, the control circuitry to model unipolar and bipolar modulation methods is simulated and their performance is checked on an induction motor and compared in MATLAB Simulink environment.