Control Strategy for Torque Ripple Reduction in Brushless DC Motors with 180-Degree Commutation

Brushless DC (BLDC) motors are widely utilized in low-cost applications due to their simple manufacturing and Hall-sensor-based control. The BLDC motors are often controlled using the 120-degree commutation logic, which naturally approximates the maximum torque per Ampere operation. The application of the 180-degree commutation mode is also possible and may be advantageous since this mode has higher dc voltage utilization, although it comes at the cost of higher torque ripple. This paper proposes a new strategy to mitigate torque ripples of the 180-degree commutated BLDC motors with PWM voltage control. This method calculates a varying duty ratio during each switching interval based on the reference and estimated electromagnetic torque. The effectiveness of the proposed torque ripple reduction algorithm is demonstrated by both simulations and experimental results on a typical industrial BLDC motor.