Torque Ripple Suppression of BLDCM With Optimal Duty Cycle and Switch State by FCS-MPC

Abstract

The traditional six-step commutation control method in brushless DC motors (BLDCM) often results in significant torque ripple, which limits its application in high-precision fields. This paper proposes a scheme that combines finite control set model predictive control (FCS-MPC) to suppress commutation torque ripple. The scheme utilizes an optimal duty cycle and optimal switch compensation state. By analyzing the mathematical model of BLDC motors, the causes of commutation torque ripple were identified. To maintain the slope of the non-commutation current unchanged, a discrete model was used to predict the non-commutation current at the next moment. The predicted current was then used to calculate the optimal duty cycle. To address the shortcomings of PWM regulation performance at high speeds, a switch insertion compensation strategy was proposed. The strategy selects the optimal switch insertion compensation state based on a cost function to offset the changes in non-commutation current. Furthermore, feedback compensation was incorporated to enhance robustness in the event of parameter mismatch. The effectiveness of this method was demonstrated through experimental and simulation results.

Keywords

• BLDCM
• model predictive control
• torque ripple
• cost function