Electromagnetic-thermal coupled analysis method for interior PMSM

This paper presents a study on the 3D (Three Dimensional) coupled analysis of electromagnetic and thermal analysis. A 3D study for both electromagnetic and thermal analyses is considered because the dominant heat sources of electrical machines are copper loss in the coils and iron loss in the core. The copper loss results from the current flowing through the coils which are located in the axial direction and have end-turns, and the iron loss (joule loss and hysteresis loss) occurs from the magnetic flux in the magnetic core with time variations and intersects. Thus, 3D rather than 2D analysis can effectively represent the loss and thermal distribution in each part of the motor. It is also necessary that an electromagnetic field analysis accounting for the temperature increase in each part should be taken into account because the heat generation from these losses transfers to the inside of the motor´s structure, changes the material properties, and finally causes an enormous impact on the motor characteristics. These physical phenomena can be handled and evaluated in the coupled analysis which is shown in the proposed procedure and thermal circuit diagram between electromagnetic and thermal analysis. Results from the experimental set-up including the fabricated 3kW interior PMSM, inverter, TMS320F28335 TI DSP with sine-triangle comparison current control method confirm the good agreement with the simulation results. Finally, the experimentally obtained results are also presented for comparison with the simulated results to verify the validity and accuracy of the proposed analysis method in the paper.