Three-Phase Model for the Circuit Simulation of Common-Mode Phenomena and Shaft Voltages in AC Motor Drive Systems

The paper presents a circuit simulation model for AC drive systems, including the capacitive and induced shaft voltages that are caused by frequency converters in AC motors. For bearing current analysis, it is essential that the common-mode voltages and currents can be predicted with a sufficient accuracy in an adequate bandwidth. The system model consists of three-phase circuit models for the power supply, the frequency converter, the motor cable, and the induction motor. The simulation results are compared with experimental results from a 1.4-MW induction motor drive. Good accuracy is achieved in predicting common-mode voltages, common-mode currents, and induced shaft voltages