Evaluation of Modulation Methods on Switching Loss, Common Mode Voltage and Current Ripple for an Open End Winding Induction Motor Drive

In dual inverter fed open end winding induction motor drives (OEWIM), the reference voltage can be synthesized either by level shifted carrier based space vector modulation (SVM) techniques or by using decoupled SVM methods. In level shifted SVM, each phase leg is switched for half the fundamental cycle and therefore has lower switching loss compared to decoupled methods. Bus clamping sequence (CS) pulse width modulation (PWM) technique also results in reduced switching loss. In this paper, decoupled and level shifted SVM methods are compared in terms of switching loss, common mode voltage (CMV) switching and stator current ripple. From the analysis, it is observed that level shifted clamping sequence SVM for a dual inverter fed OEWIM results in reduced switching loss and reduced number of CMV switching at the cost of increased stator current ripple. Compared to decoupled clamping sequence, level shifted clamping sequence has nearly 50% reduction in switching loss and CMV. Also, clamping sequence applied to decoupled method results in improved harmonic performance but has moderately increased switching loss. Various SVM methods are simulated in MATLAB Simulink for an open-loop volts per hertz (V/f) controlled induction motor drive with fixed number of samples per sector.