The twelve-phase open-winding electric drive system

characterized by low torque ripple

high energy density

and strong fault tolerance

is considered the preferred solution for low-noise electric propulsion in marine applications. However

due to the pulse width modulation (PWM) dead-time effect in the inverter

a significant zero-sequence current is generated in the low-impedance zero-sequence loop of the open-winding motor

adversely affecting motor performance and exacerbating low-frequency vibration. This paper first analyzes the impact of PWM dead-time in a three-level H-bridge inverter on the output voltage of a twelve-phase open-winding motor

revealing the interaction mechanism among PWM dead-time

zero-sequence current

and low-frequency motor vibration. Subsequently

based on the zero-axis equivalent circuit of a multiphase open-winding motor

an online PWM dead-time compensation method using a high-order extended state observer (HO-ESO) is proposed. This method dynamically compensates for the inverter’s PWM dead-time by real-time estimation and compensation of the zero-sequence error voltage. Finally

this paper establishes a simulation model and experimental platform of a three-level twelve-phase open-winding electric drive system to validate the proposed dead-time compensation method. Comparative analysis of motor vibration spectra before and after compensation demonstrates that the proposed method effectively achieves real-time dead-time compensation

suppresses the zero-sequence current induced by dead-time effects

and reduces the vibration acceleration amplitude at the characteristic frequencies of twice and four times the fundamental frequency. The proposed approach eliminates the need for current polarity detection

features straightforward implementation

and can be readily extended to other multiphase open-winding drive systems.