The twelve-phase open-winding motor system is the preferred scheme for large-capacity propulsion of ships. However

the PWM modulation strategy of the motor system inevitably produces high-amplitude common-mode voltage and zero-sequence voltage

which affects the insulation and output harmonic performance of the motor system. First

according to the characteristics of multi-phase open-winding motor

the twelve-phase open-winding motor supporting H-bridge converter is equivalent to eight three-phase single-ended converters

and the zero-sequence voltage is completely eliminated by using the simplified space vector modulation method with 120° decoupling. Then

the switching vector action order of different three-phase windings of multi-phase motor is adjusted to suppress the amplitude of common-mode voltage

and the amplitude of common-mode voltage of twelve-phase three-level H-bridge converter is reduced by more than 50% without affecting the original output harmonics and midpoint voltage control performance of H-bridge converter. Finally

the feasibility and correctness of the proposed algorithm are verified by simulation and experiment.