Torque ripple suppression method for brushless DC motor based on instantaneous-bus-voltage control strategy

Permanent magnet brushless DC Motor(BLDC) has been more and more popular in different kinds of industrial application. However, large torque ripple is a concerned problem for BLDC. PWM chopper and commutation are two major causes for torque ripple of BLDC when it is powered by a variable-frequency drive. To mitigate torque ripple, a novel control strategy called instantaneous-bus voltage control(IBVC) is proposed in this paper. Variable-bus-voltage control which has been an important trend for motor drive owing to its effectiveness in enhancing control precision is the core idea of IBVC. There are two innovations in this strategy. Firstly, to realize variable-bus-voltage, an improved multiple-output DC-DC converter(MOC) cascaded with a voltage-source inverter(VSI) is introduced as the new power topology. MOC is responsible for controlling bus-current of VSI through changing bus-voltage of VSI instantaneously while VSI is only responsible for commutation. Secondly, a voltage-selection table instead of PI current regulator is optimized-designed for optimal current control. Both simulation results and experimental results verify the validity and superiority of the proposed IBVC.