Reduction of Common Mode Voltage in Induction Motor Drives Using Various Scalar Based PWM Techniques

Abstract

This paper presents reduced Common-Mode Voltage Pulse width modulation (RCMV-PWM) algorithms for the three-phase voltage source inverter driven Induction motor. PWM methods are reviewed and their pulse patterns and common mode voltage patterns illustrated. However, the Space Vector PWM (SVPWM) algorithm gives more Common Mode Voltage (CMV) variations due to the usage of zero voltage vectors. Moreover, the conventional SVPWM algorithm needs the angle and sector information for the calculation of switching times, which increases the complexity of PWM algorithm. Hence, to reduce the complexity involved in the PWM and CMV variations various PWM algorithms have been developed using the concept of imaginary switching times of carrier based scalar approach. In the proposed approach, by adding a unique zero sequence signal to the phase voltages, the modulating signals are derived. Then by comparing the modulating signals with triangular signals, the gating pulses for the various PWM algorithms are derived. As the proposed PWM algorithms did not use the zero states, these results in reduced CMV variations. To validate the proposed algorithms, several numerical simulation studies have been carried out on scalar controlled induction motor drive. Finally, the simulation results have to be compared with the existing methods.