The technology of pulse width modulation (PWM) voltage source inverters is very mature and is widely used in traction drive inverters. But when the inverter is operating in a pulsed state, it generates a common-mode voltage (CMV). CMV will form common-mode (CM) current through the CM loop, which will pose a great threat to the motor.  In addition, the high switching frequency will produce large switching losses. In this paper, a parallel inverter is used to drive double dual-three-phase induction motors to achieve zero common-mode (Zero-CM) voltage by combining the synchronous modulation and CMV elimination modulation algorithm.  Meanwhile, a synchronous modulation strategy is adopted to reduce switching loss by making the inverter work at a lower switching frequency.  Simulation and experiment show that the proposed control algorithm can effectively suppress CMV and CM current while realizing synchronous modulation in the process of speed up and down.

traction drive; PWM; CMV; parallel inverter; synchronous modulation