Torque analysis of axial-flux permanent magnet couplers with skewed slots using electromagnetic-thermal semi-analytical model

An improved structure for axial-flux permanent magnet couplers (AFPMCs) with skewed slots is proposed to inhibit the cogging torque. Then, a novel electromagnetic-thermal semi-analytical model is presented to analyze the cogging torque, electromagnetic torque and temperature distribution. Different from conventional electromagnetic models, the proposed model takes into account the strong interaction between the electromagnetic and thermal analysis. Firstly, an exact subdomain model with multi-slice method is established in cylindrical coordinate to study the electromagnetic field. Secondly, 3-D finite element thermal model is carried out, and electromagnetic-thermal analysis is conducted. Then, cogging torque and electromagnetic torque can be obtained, and the influence of various loads on electromagnetic torque is also analyzed. In addition, the temperature distribution of the copper plate is studied. The AFPMC with skewed slots has lower temperature rise, and the temperature change along radius direction is more gently, which indicates that it is an optimal structure design. The semi-analytical predicted results are compared with the results of finite element method (FEM). The comparison results confirm the validity of the semi-analytical model.