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This study proposes the shaft voltage mitigation method according to change in parasitic capacitances of a permanent magnet synchronous motor. To consider the shaft voltage reduction in the initial motor design process without any filter, the parasitic capacitances affecting the shaft voltage are calculated using the motor geometry parameters. Then, the shaft voltage is analyzed according to change in parasitic capacitances using the equivalent circuit model and the torque characteristic is also analyzed to effectively mitigate the shaft voltage. As a result, the rotor-to-winding is determined as an appropriate parameter to mitigate the shaft voltage among the parasitic capacitances, because it affects the shaft voltage and does not affect the output torque. Finally, the shaft voltage mitigation method according to variation of rotor-to-winding capacitance is verified by experiment. [ABSTRACT FROM AUTHOR]

Fast switching and common-mode voltage of the space vector pulse-width modulation inverter output create several parasitic capacitances according to the geometry of the motor. The windings emit the electric and magnetic flux inside of the motor. They create capacitance links and electromotive force (EMF) in the shaft, respectively. Those capacitance links and EMF generate a current through two bearings of the shaft and directly reduces the bearing lifetime. In this study, we propose a new design of equivalent circuit, taking into account all parasitic capacitor components. [ABSTRACT FROM PUBLISHER]