Comprehensive Performance Comparison of Axial-Radial Hybrid Excitation Motors With Different Excitation Sources

The direct-current (DC) excitation source flux regulation hybrid excitation motor (FRHEM) is proposed to solve the problem of difficult flux regulation of permanent magnet synchronous motor (PMSM). However, the problem of output torque drop of FRHEM at the flux-weakening state has not been solved. Therefore, the alternating-current (AC) excitation source flux-torque regulation hybrid excitation motor (FTRHEM) is studied and the problem of low output torque at the flux-weakening state is solved. To clarify the influence of different excitation sources on the axial-radial hybrid excitation motor, combined with the development process of the hybrid excitation motors (HEMs), the electromagnetic performance of PMSM, FRHEM, and FTRHEM is compared and analyzed in this paper. Firstly, the topology of the three motors, flux regulation principle, and torque generation mechanism of different topologies are dynamically compared. Secondly, the comprehensive electromagnetic performances are analyzed by the three-dimensional finite-element method (3D-FEM), which includes the magnetic flux regulation performance and torque performance. On this basis, the speed-torque curve of the three motors is obtained and the advantages and disadvantages of different motors are given. Finally, the FTRHEM prototype is fabricated and tested, which verifies the results of 3D-FEM and gives the conclusion.