Research On Thermal Management Technologies Of High-speed Amorphous Alloy Permanent Magnet Motor

The high speed permanent magnet motor(HSPMM) has been widely applied in high speed machine tools, high speed centrifugal compressor and so on, since it has small size, high power density and can be directly connected with the load. However, due to the high loss and small size, the heat dissipation difficulty, it is easy to cause overheat and cause irreversible permanent magnet demagnetization, which affects the performance of the motor. Therefore, the characteristics of fluid flow inside the HSPMM, the performance of heat transfer and cooling system are significant, main research is as follows:Firstly, an experimental device for measuring the thermal conductivity of the amorphous alloy iron core was built based on infinite plate method, and the samples of several groups of amorphous alloy core were measured. Then the physical model of fluid and temperature field was established by taking a 15 kW, 30000r/min interior HSPMM as an example on the basis of computational fluid dynamics(CFD) and heat transfer theory. The fluid and temperature field was calculated using finite volume method, the temperature distribution of each part and air flow characteristics in motor was obtained. At the same time, the influence of rotor speed, surface roughness of rotor on air friction loss were analyzed based on the established fluid field.Secondly, according to the problem that the fluid flow characteristics of end region in HSPMM was poor, the influence of different rotor wafter on internal fluid flow and temperature distribution for HSPMM was studied, and fluid and temperature field was calculated using finite volume method, the temperature distribution of each part and air flow characteristics in motor with wafter was obtained. Then the influence of changing the wafter length and number on fluid and temperature field were studied, which could provide certain guidance for improving heat dissipation efficiency of rotor.Finally, according to the structure characteristics of HSPMM, “Z” axial and circumferential spiral water cooling system were established. The velocity distribution,flow resistance and temperature distribution of water cooling systems were analyed using analysis software FLUENT. Then the selection of water channel number for circumferential spiral water cooling structure was calculated and analyzed,and the influence of cooling boundary conditions on the motor was analyzed, besides, the temperature rise test for a water-cooling 20 kW permanent magnet motor was developed, and the test data were compared with the calculated results, which validated the correctness of the solution method of coupled field.