说明：  In order to improve the speed precision and stabilization of the gimbal servo system of double gimbal magnetically suspended control moment gyro, a comprehensive analysis on the reason of electromagnetic torque ripples of BLDC motor with non-ideal back EMF drives in conduction region and commutation region is presented. A novel automatic control method of torque is proposed. With this method, the current control rule is designed, and the duty cycle of PWM is regulated in real-time by measuring the wave function of back EMF. In order to eliminate the diode freewheeling of the