A new algorithm for sensorless operation of permanent magnet motors

The authors propose and investigate a novel algorithm for shaft position sensorless operation of permanent magnet motors, based on flux linkage and line current estimation. Measured line current and terminal voltage are used to estimate the flux linkage of the motor. The algorithm has a two current-loop structure, with the outer loop used to correct the position and the inner loop used to correct the estimated flux linkage. The theoretical basis of the algorithm and the individual definition of the system blocks are explained. Dependencies on motor parameters and measurement errors are discussed to show the effectiveness of the method using real data. The authors present a wide range of computed and experimental results, demonstrating the reliability of the method even during acceleration of the motor from rest