极弧系数组合优化的永磁电机齿槽转矩削弱方法

Analysis of the Optimization of the Pole Arc Combination to Reduce the Cogging Torque in PM Motors

永磁电机在高性能控制系统中应用越来越广泛,然而永磁体与有槽电枢铁心之间相互作用,产生齿槽转矩,引起电机的振动和噪声,并影响系统的控制精度。通常情况下,永磁电机各磁极的极弧系数相等。为削弱齿槽转矩,可设计相邻磁极极弧系数不等。文中采用不等极弧系数组合削弱永磁直流电机齿槽转矩,利用基于能量法和傅里叶分解的解析法得到齿槽转矩的表达式,通过分析起作用的气隙磁密的傅里叶系数,给出了使得齿槽转矩最小的极弧系数组合的确定方法。但是由于采用了一些假设,上述确定方法存在一定误差。为使齿槽转矩最小,采用全局优化方法与有限元相结合以获得最优极弧系数组合。文中对每极槽数为整数和分数的2台电机模型分别进行了解析分析和优化,结果表明:该优化方法可显著削弱齿槽转矩。

Permanent magnet motors are extensively used in high performance applications. However, the interaction between the permanent magnet and slotted armature lamination produces cogging torque, which may cause noise and vibration, In PM motors, all the PM poles usually have the same pole arc coefficients. In order to reduce the cogging torque, the adjacent PM poles can be designed with different pole arc coefficients. In this paper a novel method with different pole arc combination was adopted to reduce the cogging torque in PMDC motors. Firstly, the analytical method based on the energy method and Fourier transform is used to give the expression of the cogging torque and the method to minimize the cogging torque with pole arc combinations is presented. Since many assumptions are adopted, there are errors in the above method. To minimize the cogging torque, a global optimization algorithm（zooming algorithm） and the finite element method（FEM） are combined to find the best pole arc combination. In order to reduce the cogging torque, the adjacent PM poles can be designed with different pole arc coefficients. Two motors are analyzed and optimized with the above method and the results show that the cogging torque can be reduced notably.