An Improved Modulation Method for Suppressing High Frequency Common-Mode Voltage in SiC Motor Drive System

Abstract

High-frequency common-mode voltage generated by inverters causes severe negative effects, particularly in silicon carbide (SiC) Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs)-driven motors. Additionally, common suppression strategies would increase hardware expenses or sacrifice the switching speed of SiC devices. This article proposes an improved no-zero vector modulation strategy to suppress high-frequency common-mode voltage without increasing the cost of hardware. In this method, only nonzero vectors are utilized to reduce common-mode voltage. Firstly, the influence of different switching states on the characteristics of SiC MOSFETs has been studied by double-pulse tests, which explains why zero vectors will cause more serious voltage oscillations. Secondly, common-mode voltage suppression failure caused by the high-frequency dead zone effect has been analyzed in detail. Based on traditional Active Zero State Pulse Width Modulation (AZSPWM), complementary device conduction logic and dead-zone compensation methods are proposed. In switching moments, different turn-on logic is selected to ensure that only one switch acts, and different dead zone compensation methods are selected to deal with the common-mode suppression failure, which effectively avoids high-frequency common-mode voltage spikes. Finally, simulation and experimental results verify that the improved modulation algorithm can effectively suppress high-frequency common-mode voltage.