Coupled Magneto-Thermal Analysis of Spoke-Type Interior Permanent Magnet Synchronous Motor under the Overload Condition Considering PM Demagnetization

The spoke-type interior permanent magnet synchronous motor (STIPMSM) is used in the drive systems of electric heavy-duty truck. The drive motors are prone to the overload operation when the electric heavy-duty truck climbs a slope or operates under the heavy load. The reliability of motor is a challenge. The sustained overload capacity is an important index of STIPMSM performance. An improved multi-objective nonlinear coupled iterative calculation method for STIPMSM is proposed, which can accurately calculate the performance changes of STIPMSM under different overload conditions. The nonlinearity of the magnetic circuit and the influence of the external conditions on the material performance are considered in this method. A 650kW STIPMSM is studied. The multi-objective nonlinear coupled iterative calculation method is applied to calculate the different overload conditions. The final multi-objective convergence of physical quantities is achieved. The change of electromagnetic field and harmonics is analyzed under different load rates. A method based on nonlinear fitting for maximum sustained overload (MSO) prediction of STIPMSM is proposed. The predicted MSO operating conditions are calculated. The calculated results are agreement with the predicted results. Experiments are conducted on the STIPMSM prototype under different operating conditions. The accuracy of the calculation method is verified.