Induction motor model for the analysis of capacitive and induced shaft voltages

The paper proposes a three-phase motor model that is suitable for the analysis of bearing voltages and currents in converter-fed AC motors. Both capacitive and induced shaft voltages are taken into account. The induced shaft voltage, being the reason for high-frequency circulating bearing currents, is important in larger machines. For modeling the induced shaft voltage with a sufficient accuracy, different stator core models are compared. The motor model can be connected to three-phase circuit simulation models of frequency converters and cables. Simulation results are validated with experimental results obtained using a 1.4-MW induction motor fed by a frequency converter