A mechanical sensorless control system for salient-pole brushlessDC motor with autocalibration of estimated position angles

In this paper, a mechanical sensorless control system is reported for salient-pole brushless DC motor drives. Here, two new methods are proposed for obtaining the position angle, the accuracy of which affects the operation of the switching devices of the inverter that drives the motor. First, the method for estimating the position angle is proposed. Secondly, the correcting method for reducing the errors involved in the estimation of position angle is given. The experimental results show that the estimated position angles are calibrated automatically, and then the proposed sensorless control system can control the speed and the position angles of the motor precisely.