Simplified model predictive current control of non-sinusoidal low power brushless DC machines

Abstract

Several strategies have been proposed to control nonsinusoidal brushless DC machines (BLDCMs). However, high electromagnetic torque ripple and current overshoots occur in commutation times, which are significant problems of those strategies such as for hysteresis current controllers. This paper proposes a model predictive strategy to solve the above issues. It is simple and straightforward. Moreover, it reduces the motor torque ripple significantly and improves the response rate of the control system to the load torque variation in comparison with the conventional technique. The torque varies smoothly, and the performance of the system at commutation time is improved by eliminating the adverse effects of commutation times on the machine's current and torque. This method also operates better than the conventional controller in medium switching frequencies. The novelty of this strategy is that it employs a model predictive strategy to realize the above claims. The real implementation possibility and performance of the controller are investigated by simulations for a 60-V/180-W/300-RPM BLDCM. This paper also compares the proposed current controller with the conventional controller. The results show that the torque ripple reduces 50%, and the brake and response times are improved.

Coordinated suppression commutation torque ripple for brushless DC motor with commutation time

“…where w = 2 − d non − 2d off . According to Equation (17), when w reaches the maximum value, the commutation time t cmt is the minimum. Furthermore, the commutation time is different for different duty cycles in the constraint range.…”

“…However, the suppression strategies mentioned above are based on the hysteresis principle of the outgoing phase current, which prolong the commutation process and may even lead to the failure end of the commutation process [15][16][17]. In Refs.…”