For practical use position and speed sensorless salient-pole brushless DC motor drives

In this paper, a practical use sensorless control drive of a salient-pole brushless DC motor is proposed. In the system, the position angle and the speed at a rotating condition are estimated basically by the model reference adaptive system (MRAS). At an initial or a starting condition, the position angle is estimated by a new AC current injection method, and at a lower speed region, the estimated position angle and the speed obtained from the MRAS are corrected with a new correcting technique. The position angles and the speeds which were estimated by MRAS and the AC current injection method are compared and corrected effectively using this system. Experimental results of the estimated position angles or the speed and the variable speed control achieved are shown in the paper. From these results, the proposed sensorless speed control system may be applicable as a practical use sensorless brushless DC motor drive system.