Hybrid Analytical-Numerical Electromagnetic Vibration Calculation Method for Surface-Inserted PMSMs with Skewed Slots

The forced vibration on the surface of permanent magnet synchronous motor (PMSM) is generated by radial electromagnetic force and it is the major source of motor noise. Efficient and accurate analysis of machine vibration is extremely important for designing low-noise motors. Conventionally, the computation consumption of finite element methods is quite high, while the accuracy of analytical methods is relatively low and the skewed slots' influence are usually ignored. Therefore, the objective of this paper is to propose one hybrid analytical-numerical electromagnetic vibration calculation method to achieve fast computation and high-accuracy results simultaneously, and the skewed slots are also considered so that the applications of this method can be extended significantly. Detailed studies are carried out to validate the proposed method in this paper. Case study is conducted on one PMSM with 18 skewed slots and 16 poles, and finite element simulation is carried out to validate the proposed method. The vibration analysis is consistent with the finite element calculation results. Then one research prototype and the test rig have been developed. The experimental results verify the proposed vibration calculation method well. The hybrid method can thus accurately predict the vibration frequency and amplitude of the motor casing surface.