Cooling System Design Optimization of a High Power Density PM Traction Motor for Electric Vehicle Applications

Due to the high power density characteristics of permanent magnet (PM) traction motors and the strict loading conditions of electric vehicle (EV) engine compartments, the excessive losses inside the motors can elevate rapidly the temperature rises, deteriorate the magnetic property of PMs, limit the output torques, and even cause the overheating damages of the machines. In order to guarantee the operational reliability, it’s of vital importance to research and develop the effective, reliable and economical cooling systems for improving the working performances of the PM traction motors. In this paper, the three-dimensional (3D) fluidic-thermal coupled model of a high power density interior PM traction motor is established based on the basic theory of computational fluid dynamics (CFD) and numerical heat transfer. The fluid flow and thermal distributions are analyzed based on finite volume method (FVM), and verified by experimental results. According to the heating characteristics of the motor, the external water frame structure of the motor shell is modified to improve the cooling efficiency. Taguchi method is used to optimize the cooling structural parameters, so as to reduce the steady-state temperature rise of the motor. The research work in this paper has certain reference significance for the design and development of high power density PM traction motors used in EV applications.