Calculation And Analysis Of Fluid Field And Temperature Field Of High-speed High-power Permanent Magnet Motor

High-speed permanent magnet motor have broad application prospects due to their higher power density and smaller size.Due to the high power density of the motor,the loss per unit volume is large,and it is difficult to dissipate heat due to the small heat dissipation area.As a result,the motor is prone to excessive temperature rise,which not only easily causes demagnetization of the permanent magnets,but also affects the safe and reliable operation of the motor.Therefore,the rational design of the cooling structure is particularly important for high-speed motor.Therefore,in this paper,a series of researches are carried out with the temperature rise of high-speed permanent magnet motor as the research object.Firstly,the rotor eddy current loss and air friction loss are calculated and analyzed.Due to the influence of high frequency,the magnetic flux inside the motor changes quickly,and the eddy current loss of the rotor is large.This paper uses the finite element method to calculate the eddy current loss of the motor,and studies the change law of the eddy current loss when the protective cover material and the protective cover thickness are changed.At the same time,the computational fluid dynamics method was used to analyze the air friction loss on the surface of the jacket,the change law of air friction loss at different speeds,cooling air speeds and different air gap lengths was studied.Secondly,design cooling schemes for high-speed motor,including air-cooled,water-cooled,and hybrid cooling,and conduct coupled analysis of the fluid field and temperature field of the motor.Thirdly,in view of the problem that the temperature rise of the rotor of the high-speed permanent magnet motor is too high and the rotor is difficult to dissipate heat,a self-fan cold axial fan installed on the rotating shaft is designed for the motor.The fan that rotates with the shaft provides cooling air for the motor.By optimizing the number of axial fan blades and the installation angle,the aerodynamic performance of the fan is improved and the heat dissipation efficiency is improved.Finally,combined with the research results of each part,the final cooling parameters of the high-speed permanent magnet motor are determined,including the material,thickness,air gap length of the jacket and the corresponding axial fan parameters.Calculate the temperature rise ofthe entire motor.If the temperature rise has not fallen to a reasonable range,you need to add external air cooling until the motor temperature rise design requirements are met.By comparing the temperature rise of each part of the motor under different cooling structures,a reasonable cooling scheme is finally determined.