Research Status and Development Trends of Thermal Management Technologies for Motors

With the continuous development of the economic society, there is a growing demand for higher power density in motors, which has made motor heat dissipation issues increasingly prominent. Excessive motor temperature can lead to various problems such as geometric deformation, increased losses, insulation aging, and demagnetization of permanent magnets, all of which severely impact the performance and safety of the motor. Developing efficient and reliable thermal management technologies for motors is crucial for improving motor efficiency, durability, and safety. Building on previous research, this paper provides a comprehensive summary and analysis of the current state of thermal management technologies for motors, going beyond specific types of motors. Firstly, it outlines commonly used thermal analysis methods such as lumped parameter thermal network, finite element method, and computational fluid dynamics. The challenges encountered during the thermal analysis process are also discussed. During thermal analysis, the accuracy of the winding equivalent methods, the convective heat transfer coefficient and the contact resistance directly and greatly affect the precision of the thermal analysis. Therefore, it is crucial to prioritize in-depth discussions regarding these factors to ensure accurate thermal analysis. Based on this foundation, the development and research status of motor thermal technology including air cooling, water cooling, oil cooling, and evaporative cooling is further explored. Oil possesses good insulation performance and corrosion resistance, enabling direct contact with heat sources. Consequently, oil cooling exhibits superior heat dissipation efficiency, addressing the thermal management challenges in high-power density motors. Special emphasis is given to summarizing and analyzing oil cooling technology. Additionally, the influence of phase change materials, encapsulation materials, and heat conduction plates on motor cooling efficiency is discussed. In conclusion, it is hoped that the contents of this paper will provide valuable guidance and reference for future research in thermal management technologies for motors.