A novel Active Common-mode-voltage Compensator (ACCom) for bearing current reduction of PWM VSI-fed induction motors

In this paper, it is first observed from the experimental investigation that common-mode-voltage generated by PWM VSI is tightly related to the shaft voltage and bearing current of the driven induction motors. Based on this observation, this paper proposed a novel Active Common-mode-voltage Compensator (ACCom), which consists of a single-phase multi-level half-bridge inverter (SPMHI) and a common mode transformer. For modeling bearing currents, high frequency models of PWM inverters and induction motors are developed. Then, detailed analysis and extensive computer simulation are presented to explain the principle of ACCom and to prove the concept of ACCom. Simulation results show that ACCom significantly reduce the shaft voltage, bearing current and leakage currents of the induction motor