A five-level inverter topology for four pole induction motor drive using four two-level inverters and two isolated DC sources

In this paper, a five-level inverter configuration is presented to improve the voltage and current harmonic profile. This topology is constructed based on the stator winding configuration of a four pole induction motor. Identical voltage profile winding coils of four pole induction motor are disconnected and fed with four two-level inverters. These four inverters are supplied with two isolated dc sources to block the path for zero sequence currents through the motor phase windings. Level shifted carrier based SVPWM is used to produce the gating signals which will increase the dc bus utilization by 15%. Two two-level inverters are feeding one winding and producing three-level voltage waveform. Similarly remaining two two-level inverters are producing a three-level voltage waveform across the other winding. By providing 180° phase shift between carrier waves, multi-level voltage waveform is produced across the total winding and also first center band harmonics are cancelled. The proposed topology is simulated in MATLAB/ Simulink and experimentally verified with 5hp four pole induction motor drive.