Optimization Design and Analysis of a Linear-Rotary Permanent Magnet Actuator with Interlaced Poles

The linear rotary permanent magnet actuator (LRPMA) is a type of multidegree of freedom actuators, which can be widely applied in many fields such as aircraft driving, drilling process. This paper analyzes a novel LRPMA with interlaced poles mounted on the surface of its mover, namely, permanent magnet poles (PM_pole) and ferromagnetic poles (Fe_pole). The electromagnetic primary parameters are calculated by the numerical method, and then the finite element method (FEM) is used for parameters' optimization. The rotor diameters are optimized as the electromagnetic torque is maximized and the power is constant. The cogging torque is reduced by changing the pole-arc coefficient and the shape of the poles. The results of the optimization show that the cogging torque and cogging force can be reduced by 79.6%, 41.2%, respectively, while the average electromagnetic torque and thrust improved by 12%, 7%, respectively. In addition, compared with the traditional PM array structure, the permanent magnet material of the proposed actuator is reduced about a half. The fundamental harmonics of Back-EMF value of the proposed actuator reduced 10.9% than that of the traditional actuator, and the cogging torque and cogging force reduced 23.25%, 53.86% than that of the traditional actuator, respectively.