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In order to study the fluid flow characteristics and temperature distribution of high-speed permanent magnet synchronous motors, taking a 200kW, 20000r/min permanent magnet synchronous motor as the research object, a three-dimensional solution domain model is established based on computational fluid dynamics and heat transfer theory. The finite volume method is used to numerically analyze the temperature and fluid field of the motor. The results reveal the temperature distribution of the internal components in the motor, and confirm the strong coupling relationship between the fluid and temperature fields of the motor. The calculation results provide a reference for the optimization of the cooling system of high-speed permanent magnet synchronous motors.

A 50kW surface mounted permanent magnet synchronous motor (SPMSM) is used to explore the influence of field weakening control on electromagnetic force and vibration characteristics of SPMSMs. The air gap magnetic flux density was calculated by 2-dimensional (2-D) finite element method (FEM).The Maxwell stress tensor method (MSTM) was employed to analyze the motor's radial and tangential electromagnetic force density. By using the 2-D fast Fourier transformation, the time and spatial harmonics of the radial and tangential electromagnetic force were decomposed. In the meanwhile, vibration characteristics under different phase angles of armature current with field weakening control of the SPMSM were analyzed by the mode superposition method based on a multi-physics model. The results show that the phase angle of the armature current has a significant influence on the electromagnetic excitation force harmonics. It's effective to use the field weakening control to reduce the electromagnetic vibration of SPMSMs. This research will contribute to electromagnetic design and field weakening control strategies of SPMSMs.

Temperature rise is an essential factor affecting the safety operation of electric machines. An appropriate solving domain is the first step to consider when calculating the temperature rise. However, the effect of solving domain setting on the calculation results of electric machine temperature rise has not been deeply discussed. In this paper, a 3MW permanent magnet wind generator is taken as an example. Based on the electrical and numerical heat transfer theories, two different solving domain models are established to compare the flow thermal characteristics of the internal and external ventilated paths. The fluid velocity changes in external ventilated path, the central section temperature rise and the velocity trace distribution of the internal ventilated path are compared in detail. Furthermore, the temperature rise of each component is analyzed. It is found that the fluid development in the generator is affected by solving domain selection. The results can provide a reference for accurate calculation of temperature rise of permanent magnet wind generator.

The main objective of this paper is to elucidate the effect of rotor end structures of a large-scale air-cooled turbo-generator on the flow rate distribution and fluid flow pattern in the rotor domain. A 350 MW fully air-cooled turbo-generator is taken as an example. Based on the original ventilation structure, two optimization schemes of adding wind deflectors and small fans to the end of the rotor are proposed. The finite volume method is used to solve the fluid field in the generator with different rotor end structures. The air volume distribution in each wind area of the generator is taken as the basis for checking the accuracy of the calculation. Under different schemes, the wind path direction, flow rate and fluid velocity distribution in the radial ventilation ducts, subslots and crescent slots of the rotor are compared and analyzed. The effects of these schemes on the overall flow rate distribution and the fluid parameter distribution characteristics in each rotor ventilation ducts are determined.