Vector control of surface mounted permanent magnet motor without any rotational transducer

This paper presents a new vector control algorithm of a surface mounted permanent magnet motor (SMPMM) without any rotational transducer. Originally, the SMPMM does not have any magnetic saliency in its structure, but it has a little magnetic saliency due to the saturation by the flux of the permanent magnet. Moreover, it varies according to the load conditions and the control performance of schemes using the saliency can be easily degraded. To prevent it and to improve the performance of the proposed algorithm, the saliency of a SMPMM under various load conditions is analyzed. In the proposed algorithm, the saliency or impedance difference related to the saliency is utilized in order to estimate the position and speed of the rotor. And the high frequency signal is injected into the motor to measure the impedance difference and also to enhance the control performance of the system. The experimental results verify the effectiveness of the proposed sensorless algorithm.