A Universal Coupled Predictive Model for Motor Bearing Voltage and Multisource Shaft Voltage

This study proposes a universal motor model that accurately predicts both bearing voltages (BVs) and multisource shaft voltages (SVs). The increasingly severe problems of bearing currents (BCs) and electric-erosion faults have made the precise predictions thereof particularly crucial. Hence, three types of SVs induced by the BVs, high-frequency (HF) common-mode (CM) current, and HF difference current are calculated in this study. Furthermore, a coupled calculation model for BV and multisource SVs that considers the impacts of HF circulating BC on the grounding circuit is proposed. To accurately calculate HF CM and difference currents, a broadband grounding circuit model that simultaneously considers CM and differential-mode (DM) effects is established. A universal predictive model for the coupling between the motor BV and multisource SVs is constructed. Experiments showed that this model precisely predicted the amplitude-frequency characteristics of various signals, such as grounding currents, CM voltages, BVs, three types of SVs, and BCs.