Design and Implementation of Closed-Loop Controller with Current Sensors for Brushless DC Motor Drives

Abstract

This paper is concerned with the design and implementation of closed-loop controller with current sensors for brushless DC motor drives to yield good speed regulation, low current harmonic and stable output speed. The design of controller is conducted by digitizing the mathematical model of brushless DC motors. The regulation and limitation of control parameters are also studied. The saliency of brushless DC motor yields larger quadrature-axis inductance than that of the direct-axis. This results in reluctance torque accordingly. By appropriately adjusting the direct-axis current, the reluctance torque can be controlled to achieve high-efficiency operation. The proposed control strategy will not only yield optimal efficiency but also result in the immunity of performance to the variation of machine parameters. A predicted current estimator is proposed to function under stationary frame for harmonic current suppression. In this paper, the mathematical models of the brushless DC motor is built and simulated by Matlab/Simulink. Then, a high-performance and low-cost digital signal processor (DSP, TMS320F28335) is used to control the system for reducing the circuit complexity. A digital control system for 750 W brushless DC motor is realized. Experimental results indicate that the total harmonic distortion of current is reduced by the proposed closed-loop controller with current sensor.