Brushless DC Motor Common-mode Voltage Analysis

Abstract

Brushless DC motors (BLDCMs) with their own performance of obvious advantages: good speed regulation performance and high efficiency. BLDCMs have continuously replaced brushed DC and induction motors in many competitive fields and obtained more extensive applications. The common-mode voltage (CMV) in the motor parasitic capacitance coupling in the motor shaft induces the shaft voltage. It then triggers the shaft current, resulting in electrical corrosion of the bearing. It is necessary to conduct a systematic scientific analysis of its CMV. For different modulation methods, the phase voltages under three conditions without PWM modulation, HPWM_LPWM modulation, and HPWM_LON modulation are studied, FFT, and then the CMV is analyzed. Then, the correctness of the analysis is verified by simulation analysis.