Brushless DC motors are often used as the power sources for modern ship electric propulsion systems. Due to the electromagnetic torque ripple of the motor, the traditional control method reduces the drive performance of the motor under load changes. Aiming at the problem of the torque ripple of the DC brushless motor during a non- commutation period, this paper analysis the reasons for the torque ripple caused by pulse- width modulation (PWM), and proposes a PWM_ON_PWM method to suppress the torque ripple of the DC brushless motor. Based on the mathematical model of a DC brushless motor, this method adopts a double closed-loop control method based on fuzzy control to suppress the torque ripple of the DC brushless motor. The fuzzy control technology is integrated into the parameter tuning process of the proportional–integral–derivative (PID) controller to effectively improve the stability of the motor control system. Under the Matlab/Simulink platform, the response performance of different PID control methods and the torque characteristics of different PWM modulation methods are simulated and compared. The results show that the fuzzy adaptive PID control method has good dynamic response performance. It is verified that the PWM_ON_PWM modulation method can effectively suppress the torque ripple of the motor during non-commutation period, improve the stability of the double closed-loop control system and meet the driving performance of the motor under different load conditions.

In order to meet the operation requirements of the beam supply with multiworking conditions, multi-modes and high efficiency, a dual-mode hybrid output control method combining phase-shifting and pulse-width dual-mode modulation technology with secondary side series-parallel operation is proposed. In this paper, the structure and working mode of the new dual full-bridge topology are firstly analyzed. Secondly, the main circuit parameters are designed according to the power performance indicators, and the losses under two control modes of phase shift and pulse width are calculated. Finally, comparing the losses of these two control methods, and combining the series-parallel operation mode of the secondary side of the transformer, a dual-mode switching control method of the beam supply is designed. In order to verify the rationality of the dual-mode mixed output control method, a principle prototype with a rated capacity of 2 kW, a rated voltage of 1 800 V and a switching frequency of 50 kHz was used for verification. Experiments show the effectiveness and superiority of the dual-mode hybrid output control method.