关键词: 无刷直流电动机, 轴电蚀, 轴电压, 绝缘转子, 共模等效电路

Abstract: BLDC motor driven by PWM inverter widely used to drive air conditioner fan has a large issue, the shaft voltage coupled by the commom-mode voltage under the action of the stray capacitance of the motor brake down the grease, resulting in the bearing erosion with bearing ball and groove damaged.Based on the mechanism of bearing erosion,the structure was built with different kinds of stray capacitance in motor and equivalent circuit model for common mode.An insulated rotor using an insulating layer added in the middle of rotor core was proposed to increase its own capacitance, and the shaft voltage was reduced under the guidance of simulation.The concept of discharge rate was put forward, and bearing current and discharge rate were combined to improve and enrich the bearing erosion risk evaluation system.

Key words: brushless DC motor(BLDCM), bearing electrical corrosion, shaft voltage, insulated rotor, equivalent circuit for common-mode