Analysis and calculation of capacitance parameters in induction machines to predict shaft voltage

The modeling and calculation of coupling capacitances of motors are investigated in this paper. These capacitances are key parameters in predicting shaft voltage in the common mode model of inverter-asynchronous motor drive system. Based on the structure of motors, the analytic calculation of capacitance is carried out. According to the partition capacitance theory, finite element analysis is adopted to achieve these capacitances. Then an improved finite element model of motor´s winding is proposed to acquire rational results. The measurement of capacitances is introduced. The calculation results of capacitances are compared with the experimental results, which show the validity of the improved model.