Research on Bearing Current Detection Method of High-speed Motor Driven by PWM Inverter

With the wide application of PWM inverter, bearing failure caused by bearing current seriously affects the reliability and safety of the driving system. Accurate measurement of bearing current is the key to evaluate the simplified model of bearing current and analyze the influence of bearing current. This paper adapts a method for measuring bearing current. Firstly, this paper analyzes the capacitance model of high-speed motor bearings represented by PMSM. Secondly, this paper analyzes and calculates the stray capacitance, and performs finite element calculation for a certain machine. Comparing the analysis results, a method for detecting the shaft current is described. Finally, experimental tests for stray capacitance will be given, the measured stray capacitance value is substituted into the MATLAB simulation model. Based on the proposed detection method, the shaft current waveform is measured to verify the accuracy.