Temperature Rise Modeling And Cooling Performance Analysis Of Permanent Magnet Synchronous Motor

Motor is the core component of an electric car. It inevitably produces energy loss in the operation process. This loss is the main heat source. If the loss of per unit volume is too large, or the cooling performance is bad,it may lead to high temperature, shorten the service life of the motor, or even damage the motor.This paper mainly studied the loss and temperature distribution of the permanent magnet synchronous motor, and an optimization design of cooling system was put forward, The main work of this thesis is as follows.First of all, according to the basic knowledge of electrical motor, in this paper, permanent magnet synchronous motor simulation model was established. The influence of rotating speed and load on copper loss was analyzed. Three methods has been used to calculate core loss, and experimental results show that the calculation results which respectively used Fourier decomposition on radial and tangential flux density to calculate core loss is closer to the actual value. The eddy current loss of the rotor has been calculated with finite element method, and the simulation found that the motor rotor eddy current loss was very small, even can be ignored. With the formula method, mechanical loss under different speed has been calculated.Secondly, according to the theory of heat transfer and fluid mechanics knowledge, this paper has researched the cooling performance and the flow characteristics of the fluid. The thermal network computing model of the motor has been established to calculate the average temperature of each node in motor. Research shows that the temperature of each node slightlydecreases with the increase of inlet flow, while increases almost the same amount with the increase of inlet water temperature.Thirdly, this paper studied the influence of motor cooling structure on cooling performance through the simplified model. And the size of the spiral channel was established. The 3 D finite element simulation model of motor temperature rise was established, and the temperature distribution in motor parts was gotten and compared with the results of thermal network model. Research shows that the results of finite element method and thermal network calculation are consistent. But the calculation result of finite element method is more intuitive and concrete.Finally, the motor temperature rise test was designed. Besides, in order to prove that the motor temperature rise simulation model is correct,the temperature of each point when motor worked at the rated conditions was collected to compare with the simulation value. On the basis of experiment and simulation, an optimization scheme was proposed. It provided a reference for motor cooling system design.