Simplified Control for Torque and Speed Ripple Mitigation in Brushless DC Motors

Abstract

Brushless DC motors are characterized by their reliability, low inertia, fast response, and low maintenance. Unlike the conventional DC machines, the BLDC uses permanent magnets in place of brushes, resulting in lower maintenance requirements. Brushless DC motors produce constant torque under ideal conditions, with a trapezoidal back electromotive force (emf). However, torque ripple appears in the output torque in practice. Utilizing power electronic components for commutation in brushless DC motors causes harmonics to be generated in the armature current. This paper proposed a simplified circuit to minimize torque and speed waveform ripples. The circuit incorporates a simple filter, PI controller, and PWM, eliminating the need for a high computational processor. This enables easy execution and reduces the control circuit's energy footprint, resulting in low running costs. The proposed circuit was simulated using PSIM software and the results confirm the ability of the circuit to minimize the torque and speed ripples