Initial Rotor Position Estimation of Sensorless Salient-Pole Brushless DC Motor

This paper presents an initial rotor position estimation of the position-sensorless salient-pole brushless dc motor. To estimate the initial rotor position, the rectangular pulsewise voltages are applied from the inverter to the motor. Since the three-phase winding inductances are a function of the rotor position, the different line current responses are obtained according to the rotor position. The current peaks are used to estimate the initial rotor position. The estimation is very practical because the estimation is not influenced by the motor parameter variation and the estimation process time is as short as 1 msec.The proposed estimation algorithm of the initial rotor position is verified by experiment with 6-pole 200W test motor. The experiment shows the successful position estimation within 12.9-degree error.