Research on the Method of Suppressing the End Detent Force of Permanent Magnet Linear Synchronous Motor Based on Stepped Double Auxiliary Pole

Permanent magnet linear synchronous motors have the advantages of high thrust density, high acceleration, high speed, and high efficiency, which are widely used in CNC lathes, lithography machines, rail transportation, etc. In high-speed, high-precision servo control systems, detent force fluctuation caused by end effect can easily cause problems such as speed fluctuation, mechanical vibration and electromagnetic noise, which affect the servo performance of permanent magnet linear synchronous motors. Aiming at the detent force fluctuation caused by the end effect of permanent magnet linear synchronous motor, this paper proposes a stepped double auxiliary pole method. The method has a good suppression effect on the end normal force fluctuation and the end thrust fluctuation, which improves the servo performance of the permanent magnet linear synchronous motor in the high-precision servo system. In the traditional methods of suppressing the fluctuation of end detent force, two common methods are using a magnetic isolation aluminum plate and optimizing the auxiliary pole size. The former needs a magnetic isolation aluminum plate to connect the auxiliary pole and the primary mover. Therefore, it needs to add the connection device to connect those three parts. The connection device complicates the auxiliary pole part and increases manufacturing difficulty. The latter does not change the manufacturing process, but in the early design process, the optimum size of the auxiliary needs to be considered. Compared with these two methods, the one proposed in this paper avoids the complex structure of magnetic isolation aluminum plate, the stepped double auxiliary pole is integrated with the primary mover. Moreover, it has a fixed structure with optimum size. Therefore, the method in the paper does not change the manufacturing process, improves the strength of the initial pole structure, and reduces design period. Finally, the finite element analysis by ANSYS was performed to illustrate the correctness and effectiveness of the method.