Improved brushless DC motor speed controller with digital signal processor

Brushless motors are used in many applications owing to their advantages. In most of the applications, conventional control methods with a hysteresis band (HB) controller are used. An improved speed and current control scheme for brushless DC motors with a trapezoidal shape back EMF is presented. Instead of the conventional HB and proportional-integral (PI) controllers, a fuzzy logic controller that is independent of motor equations and based on expert knowledge has been employed for current and also for speed regulation; thereby, the disadvantages of the HB are eliminated and the overall performance of the controller is enhanced. Experimental studies have been carried out with a TMS320F2812 digital signal processor. The presented control scheme has been validated through comparative experiments with the fuzzy logic speed and HB current controller. The results show that the proposed control scheme operates satisfactorily and provides a constant switching frequency.