Accurate initial pole-position estimation of surface PM-LSM in the position control

This paper proposes a newly developed algorithm for the initial pole-position estimation of a surface (non-salient) permanent magnet linear synchronous motor, which is carried out under the full position closed loop control without any pole sensors and is insensitive to the motor parameters. This is based on the principle that the initial pole-position is simply calculated by the reverse trigonometric function using the two feedback currents in the position closed loop control. The proposed algorithm consists of the predefined reference position profile, the information of feedback currents, speed, and relative position, and the reverse trigonometric function for the initial-pole position estimation. Compared to the published researches, the proposed algorithm is simple in implementation and is more accurate in estimation even close to standstill through the full closed control. This algorithm can be widely applied without any limitations of motor structures. The effectiveness of the proposed algorithm will be verified through mathematical analysis and simulations.