A Hybrid PWM Strategy with Reduced Common-mode Voltage and Extended Output Voltage Linearity for Adjustable Speed Drives

Common-mode voltage (CMV), introduced by employing conventional space vector pulse-width modulation (SVPWM) in voltage source inverters, can be detrimental to inverter-fed electric machines electric machines. The utilization of zero voltage vectors produces considerable common-mode voltages, which could result in premature bearing failures. In this paper, a hybrid PWM strategy, eliminating the use of zero voltage vectors, is proposed to reduce CMV within and beyond the rated speed in adjustable speed drives (ASDs). The proposed hybrid PWM strategy features the combination of remote state PWM (RSPWM) and near state PWM (NSPWM) across a wide range of output frequencies with guaranteed output voltage linearity. Simulation and experimental results demonstrate the effectiveness of the proposed hybrid PWM strategy in CMV reduction for ASDs.