Four Rotor Structures for High Speed Interior Permanent Magnet Motor Considering Mechanical, Electromagnetic and Thermal Performance

For high speed interior permanent magnet (IPM) motor, the measures to improve rotor strength inevitably affect electromagnetic, loss and temperature characteristics, which makes it difficult to judge which rotor structure is better in design. In this paper, four different rotor structures of high-speed IPM motors are compared comprehensively, including rotor stress, electromagnetic and loss characteristics, and temperature distribution. Firstly, four rotor structures of 140 kW, 18 000 rpm high-speed IPM motor are introduced, and effects of main factors on rotor stress and electromagnetic characteristics for four rotor structures are analyzed comprehensively. Secondly, the effect of manufacturing tolerances on rotor stress is also performed for four rotor structures. Thirdly, the design parameters of four rotor structures are optimized by considering rotor stress, electromagnetic and loss characteristics. Then, the multiphysics performance of the four rotor structures is compared, including the rotor stress, electromagnetic performance, loss and temperature. In addition, rotor mechanical strength at different surface linear velocities is analyzed by scaling up rotor outer diameters and rotor design parameters. Finally, to verify the theoretical analysis of this paper, two rotor structures are manufactured and tested for electromagnetic, rotor strength and temperature characteristics.