Analysis of Stator Vibration Modal Characteristics of Permanent Magnet Synchronous Motors Based on a Layered Theory

A new layering theory is proposed for the stator of high-voltage flat-wire motors for electric vehicles (EVs) to accurately calculate its natural frequency (NF) and frequency response function (FRF), which reduces the influence of motor nonlinearity. Firstly, based on the layering method, the analytical formula for stator core stiffness layering is derived, and the formula for the stator system NF after layering is obtained. Secondly, the modal and FRF of an EV 800V flat-wire motor stator are simulated before and after layering using finite elements, and the stator is tested for modal and FRF using the single-point excitation multi-point response hammering method. By comparing the analytical calculation, finite element simulation and experimental results, it is found that the analytical calculation accuracy of the NF after layering is improved by 6.22% on average, and on the basis of the existing NF simulation accuracy of 8%, the simulation accuracy of each order of NF after layering is controlled within 1%, among which the simulation accuracy of the (0, 0) order is improved by 6.33%. The average amplitude of the FRF after layering is 13.49% more accurate than before layering, and the simulated waveform of the FRF is generally closer to the experimental waveform. Finally, a comparison of the simulation and test results before and after the layering of the stator core with flat wire windings again verifies that the layering method can improve the accuracy of the stator modal calculations. The layering theory is also applicable to other motors with large differences in tooth and yoke stiffness structures.