Research On Fluid-thermal Coupling Of 200kW High Speed Permanent Magnet Synchronous Motor

High speed motor has high speed and high power density,its volume is far less than the same medium and low speed motor,which reduces the material consumption and reduces the cost.The high-speed motor can also be directly connected with the original motive or load,which saves the transmission device,reduces the noise and improves the efficiency of the transmission system.Because of these advantages of high-speed motor,it has good application prospects in electric vehicle,energy storage flywheel,cycle refrigeration system,high-speed grinder,textile and so on.Because of its high working frequency,large unit volume loss and difficulty in heat dissipation of the rotor,it easily causes the irreversible demagnetization of the permanent magnet to cause the irreversible demagnetization,which threatens the safe operation of the motor.Therefore,the coupling calculation of the three-dimensional fluid field and the temperature field is carried out to the high speed permanent magnet motor,and a reasonable cold structure is designed to improve the cooling effect of the motor and the cooling effect of the motor.It is very important to ensure the safe and stable operation of the motor.In order to solve the above problems,the mathematical model of 200 kW and 20000r/min high-speed PMSM(high speed permanent magnet synchronous motor)combined with air cooling and water cooling is established in this dissertation.A reasonable basic hypothesis is put forward in combination with the basic principles of numerical heat transfer and computational fluid mechanics and the coupling mechanism of flow and heat.The physical solution model is set up,and the reasonable boundary conditions are given.The finite element method is used to calculate the fluid field and temperature field of the high speed permanent magnet motor,and the rheological characteristics and the temperature rise distribution of the motor are obtained.The flow law of cooling water in the water jacket and the cooling air at the end of the motor is analyzed in detail,and the temperature distribution law of the whole motor is further analyzed in combination with the fluid field,including the distribution of the axial and radial temperature of the motor,and the main heating components(windings,stator core and permanent magnet)are systematically carried out.By changing the structure of the inlet and outlet of the cooling air of the motor,the ventilation cooling mode of the motor is changed,and the axial cooling is forced along the air gap.The results of the calculation of the temperature field of the two schemes and the temperature field of each component of the motor are compared and analyzed,and some useful conclusions are obtained.