Design and optimization of a high-bandwidth low-speed high-torque permanent magnetic synchronous motor

In order to get a better dynamic response for actuator in condition of low-speed, a permanent magnet synchronous motor (PMSM) in direct-drive application with the characteristics of high-bandwidth, low-speed and high-torque was designed in this paper. Based on the requirement of high-bandwidth, the motor's inertia should be kept low to acquire a large acceleration. The limitation of space size makes motor work in non-linear region, which will increase the electrical capacity. This paper took the relationship between inertia, physical size and electrical capacity into consideration and an optimal result was selected by the method of cyclic iteration. According to the characteristics of large-torque motors, the reason of low power factor was further analyzed. In order to improve the motor performance, optimal design was taken on modified Taguchi method based on time-stepping Finite Element Method (FEM) in this paper. First, five structural parameters (pole-arc coefficient, etc.) were taken as optimization variables and four motor performance indexes (power factor, etc.) as optimization objectives. Then, the multi-objective multivariable optimization was adopted. Finally, The results of FEM and prototype experiment verified the advantage and effectiveness of the modified Taguchi method.