Temperature Field Analysis of Oil-Cooled Heat Dissipation in High-Speed Permanent Magnet Synchronous Motor

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With the development of high-speed permanent magnet synchronous motors (PMSM), the requirements for speed are getting higher and higher, and the power density increase is getting bigger and bigger. However, too high a loss density will cause motor heat dissipation difficulties, resulting in motor insulation aging and permanent synchronous magnet demagnetization failure, which seriously affects the safe operation of the motor. Therefore, it is necessary to analyze the fluid field and temperature field for oil-cooled high-speed PMSM. In this paper, a 40 kW back-wound oil-cooled high-speed PMSM is used as the research object. Firstly, a three-dimensional fluid-solid coupled heat transfer model of high-speed PMSM is established based on the parameters of the motor, and the fluid flow characteristics inside the motor are analyzed based on fluid dynamics and heat transfer theory, and then the overall and local temperature rise distributions of the motor are compared and analyzed to reveal the influence of the temperature rise of each component inside the high-speed permanent magnet synchronous motor after being cooled by the cooling structure. Secondly, based on the finite element model, the motor temperature rises and oil flow characteristics with oil flow rate are analyzed to come up with an optimized solution. Finally, the accuracy of the analysis method is verified by conducting temperature rise experiments on the prototype.