Sensorless control and initial position estimation of salient-pole brushless DC motor

This paper presents a position sensorless drive and an initial rotor position estimation for a salient-pole brushless DC motor with a sinusoidal flux distribution. To estimate the position and back EMF, the controller calculates the motor current by using the estimated position and back EMF of the motor model. The difference between the actual and the calculated currents is used to estimate the position and back EMF. The initial rotor position at standstill should be estimated for stable starting without temporary reverse revolution. The principle of the initial position estimation relies on the saliency of the motor and uses the current response difference due to the rotor position. To confirm the effectiveness of the proposed algorithm, experimental results using a 6-pole 200 W test motor are shown.