Simulation-Based Shaft Voltage Reduction through Structural Modifications for Bearing Electrical-Erosion Prevention

Abstract

The increased shaft voltage, resulting from high-speed PWM switching and elevated DC-link voltage, causes bearing damage, which in turn leads to increased noise and vibration, as well as reduced system reliability. To mitigate this problem, this paper proposes a simulation-based method for predicting and reducing shaft voltage. The common-mode voltage obtained from the inverter-motor simulation and the parasitic capacitance calculated based on the motor structure are used to construct an equivalent circuit for parasitic capacitance simulation, through which the shaft voltage can be derived. By incorporating additional parasitic capacitance into the motor design, specifically by integrating an insulating shaft sleeve, the shaft voltage can be effectively reduced. The proposed method can be applied regardless of the motor design and effectively reduces the shaft voltage.