A new sensorless permanent magnet synchronous motor algorithm based on algebraic method

In this paper, a new algorithm for position and speed estimation in permanent magnet synchronous motors is presented, which is based on the high frequency permanent motor model and on high frequency signal injection, uses an algebraic approach and is aimed to low speed range applications. High frequency injection allows, by means of simple mathematical relationships, the estimation of motor characteristic inductances. The machine inductances are characterized by a certain degree of position dependent magnetic saliency, as a function of the shaft position, in particular the mutual inductance value, which is proportional to the error between the true angle and an estimated angle value. The angle error is utilized as error signal, in a phase locked loop technique, in order to track the motor position and speed. Simulation and experimental results are presented which confirm the validity of the proposed solution.