Optimized PWM Scheme with Minimized Common-mode Voltage Amplitude and Frequency in VSI-Fed Motor Drives

Abstract

Common-mode voltage (CMV) is of great concern in voltage source inverter (VSI)-fed motor drive systems. The pulsating CMV introduced by the VSI contributes to significant common-mode and bearing currents, which may lead to electromagnetic interference (EMI) problems and bearing failure. The presence of highest CMV occurs in a two-level VSI when zero voltage vectors are engaged. To combat the adverse effect by CMV, an integrated active zero-state switch (IAZS) can be adopted for the VSI to achieve reduced CMV when zero voltage vectors are desired. In this paper, an optimized pulse-width modulation (PWM) scheme is proposed to fully exploit the IAZS. The new zero voltage vector initiated by IAZS plays an important role in minimizing both amplitude and frequency in CMV. Simulation as well as experimental results have validated the effectiveness of the proposed modulation scheme with IAZS.