Enhancing Bearing Reliability in Inverter-Fed IPMSMs Drive: Control Method for Low-Speed Operation

Voltage source inverters are widely used in industry due to their high control performance and efficiency in electric motor drive systems. The output voltage of inverter at the switching instance causes the generation of bearing current, leading to bearing damage. To investigate the impact of bearing currents on bearing damage, this paper first analyzes the mechanism of bearing currents. Then, a control method for bearing current reduction is proposed. The two-phase pulse-width modulation method that considers the saliency of IPMSM and a capacitive filter topology is presented and verified by experiments in commercial electric vehicle drive system. As a result, the bearing current is reduced by 91% in comparison with space vector pulse-width modulation.