Torque Ripple Reduction in Brushless DC Motors with 180° Commutation

Hall-sensor-based brushless DC (BLDC) motors are utilized extensively in low-cost applications due to their manufacturing simplicity and ease of control. Often, BLDC motors are controlled using the 120° commutation logic, which naturally approximates the maximum torque per ampere (MTPA) operation. However, in some applications, the 180° commutation is preferred since it allows higher DC voltage utilization and continuous phase currents, although it comes at the cost of higher torque ripple. This paper proposes a new torque control strategy to reduce the torque ripple in the 180°-commutated BLDC motors. The proposed method dynamically adjusts the duty cycle within each switching interval based on the reference, the estimated electromagnetic torque, and the derivative of the torque. The proposed method is analyzed under different speeds and back EMF shapes, and its effectiveness is validated through simulation and experimental results on a typical industrial BLDC motor.