Scalar Based Generalized PWM Algorithm for Vector Controlled Induction Motor Drive with Reduced Complexity

Abstract

This paper presents a simple scalar based (carrier comparison based) generalized pulse width modulation (GPWM) algorithm for 2-level voltage source inverter fed vector controlled induction motor drive. Though the classical vector control technique gives fast dynamic response due to the decoupled control, it gives variable switching frequency operation and gives more harmonic distortion in the line current. This can be overcome by using the space vector PWM (SVPWM) algorithm. But, the complexity involved is high in the classical SVPWM algorithm due to the angle and sector calculations. Moreover, it gives more switching losses due to the continuous modulating signal. The proposed algorithm generates the modulating signals by using the instantaneous phase voltages only and hence reduces the complexity. By varying a constant in the unique zero sequence signal various discontinuous PWM (DPWM) algorithms along with the SVPWM algorithm can be generated at all modulation indices (linear and over modulation regions). To show the effectiveness of the proposed GPWM algorithm, the numerical simulation studies have been carried out and results are presented and compared