應用電磁與熱傳模擬於電動車感應馬達改良設計

Abstract

本研究以改良電動車感應馬達的連續工作能力作為研究主軸，並同時以減少發熱量和增加散熱能力兩個方法進行。減少發熱量的方法是以磁路改良來提高效率，在不更動馬達大多數幾何尺寸下，依序改變繞線節距、定子、轉子槽形的參數進行效率分析，找到效率最佳的參數值作為磁路改良設計方案。增加散熱能力的方法則是先以熱路模型軟體建立熱傳模型來討論馬達散熱的改良方向，之後針對冷卻水與內部空氣的流場進行分析與改良設計，比較哪種水道有較好的散熱能力，並為內部空氣設計新的散熱途徑，將空氣的熱量能夠直接傳至水套。最後要將磁路與散熱的改良設計結合，並加入會因溫度變化的電阻值來分析效率，得到馬達在連續工作三十分鐘後的溫升大小與平均效率，由此找出馬達在多大的功率下能連續工作三十分鐘，證明改良後的馬達連續工作能力確有提升。

The purpose of this study is to improve the continuous operation ability of induction motor for electric vehicle. To achieve this, we tried reducing heat sources and increasing heat dissipation at the same time. To reduce heat sources without changing most of the geometry of the motor, the magnetic circuit was optimized to increase efficiency. We adjusted the parameters of winding pitch, stator and rotor slot shapes sequentially and find out the combination of parameter values with the highest efficiency as a magnetic circuit optimization solution. To increase the heat dissipation, we used a lumped-circuit thermal model software to create a heat transfer model of the motor to investigate the strategies to improve motor cooling. One the one hand, we improved the design for the flow fields of cooling water to figure out the water channel form with better cooling ability. On the other hand, we designed a new cooling path for internal air that can directly transfer heat from air to the water jacket. Finally, we integrated the design with the optimized magnetic circuit and motor cooling and analyzed efficiency in consideration of temperature-dependent resistance. We obtained the temperature rise and the average efficiency of the motor operating for 30 minutes continuously. Thus, we found out the maximal power with which the motor can operate continuously for 30 minutes. To conclude, the continuous operation ability of the improved motor design was indeed promoted.