New initial pole position estimation of surface PM-LSM using reference currents

This paper proposes a new algorithm for the initial pole-position estimation of a surface permanent magnet linear synchronous motor (PM-LSM), which is carried out under closed loop control without a pole sensor and is insensitive to the motor parameters. This is based on the principle that the initial pole-position (IPP) is calculated by the reverse trigonometric function using two reference currents, which are informed from the speed controller. Compared to the published researches, the proposed algorithm does not utilize the impedance ratio like the general methods and it can be widely applied without the limitation of the motor structures. The effectiveness of the proposed algorithm is verified by testing a surface PM-LSM with large cogging, which results show the IPP is well estimated within a satisfied moving-distance and a shorter estimation taken-time even if a large disturbance such as cogging is existed.