Temperature rise characteristics of permanent magnet synchronous motor considering boiling heat transfer

The temperature rise characteristics of PMSM (permanent magnet synchronous motor) during operation were studied under the condition of BHT (boiling heat transfer) in cooling water. The subcooling boiling heat transfer model, RPI (Rensselaer polytechnic institute), was used to calculate and improve the computational accuracy of simulation results. The experiments have shown that, when the motor was tested and simulated after preheating, the temperature rise characteristics were similar to test data because the boiling heat transfer phenomenon of the motor was taken into account, with an error of 1.7%, which was more accurate than the error of 7.5% without boiling. Therefore, from the results obtained from the experiments, the phenomenon of boiling heat transfer in cooling system has a significant effect on the temperature rise characteristic of the motor, which should be regarded as an important factor. Due to the influence of two-phase flow boiling heat transfer, the temperature rise of the motor in the plain areas is 4–5 °C higher than that in the high altitude areas. Consequently, if the motor is operated in high altitude areas, its temperature rise characteristic has better effect compared with plain area. Additionally, when BHT in cooling water is considered, the temperature of the motor drops as the rate of flow increases. In the meantime, the temperature difference between the minimum flow rate and the maximum flow rate is about 1 °C, which means that the increase in rate of flow can enhance the boiling heat transfer effect.