An Active Common-Mode Voltage Compensation Method for Three-Phase Induction Motor Drives

Pulse Width Modulated (PWM) voltage source inverters are widely used to power induction motors in industrial applications. However, they generate common-mode voltage (CMV), which induces high shaft voltages and bearing currents, leading to premature motor failures. This paper proposes a novel active cancellation method to compensate for the CMV in high-voltage induction motor drives. The method utilizes Y-configured resistors for CMV detection and a push–pull amplifier with MOSFETs to generate reproduced CMV (RCMV). The RCMV is applied to the motor frame via an isolation transformer, effectively reducing the CMV-induced common-mode current (CMC). The proposed method achieves a significant reduction in the CMC, from 1.5 A to 4 mA peak-to-peak in a simulation and from 2.7 A to 57 mA peak in experiments with a 1.1 kW, 415 V/60 Hz motor. This cost-effective approach enhances motor drive reliability and mitigates electromagnetic interference (EMI), making it suitable for high-voltage applications.