| In recent years,with the rapid development of high-speed motor,it is widely used in high-speed machine tools,micro gas turbines,centrifugal compressors,energy storage flywheels and other fields.The permanent magnet motor has the advantages of simple structure,high power density and no excitation loss,and becomes the first choice of high-speed motor design.Under the traditional technology,the manufacturing of high-speed permanent magnet motor mostly adopts the method of magnetizing first and then assembling.The heat fitting process of the retaining sleeve of the rotor and the permanent magnets will produce a high temperature environment,which will cause high temperature demagnetization of the pre-magnetized permanent magnets.The post-assembly magnetization technology adopts the method of first assembling and then magnetizing.During the assembling process,the permanent magnets do not have magnetism,which fundamentally solves the problem of high temperature demagnetization in the process of heat fitting.In addition,the post-assembly magnetization technology can effectively improve the production efficiency of permanent magnet motor,reduce the cost and ensure the personal safety of production personnel,and has good application prospects.Based on the requirement of the post-assembly magnetization of a 300k W two pole high speed permanent magnet rotor,the hysteresis model of Sm2Co17 permanent magnet material has been constructed.To optimize the structure and energy of the coil,the saddle-shaped topology and inner support structure of the coil have been proposed.And the influencing factors of eddy current effect in the structure during magnetization were analyzed.The post-assembly magnetization coil was designed by combining the parameters of power supply system and coil,which could produce a pulsed transverse magnetizing field with a peak intensity of 6T in a bore with a diameter of 84mm and a length of 270mm.The prototype was manufactured and tested.For the first time in China,the coil has successfully realized the post-assembly magnetization of this type of rotor.In this paper,the hysteresis model of Sm2Co17 permanent magnet material has been built to simulate the process of magnetization and demagnetization.The magnetization experiment of Sm2Co17 permanent magnet was carried out and the J-A model was selected as the hysteresis model of the material to realize the dynamic simulation of magnetization process.Due to the identification requirements of the parameters in J-A model,a parameter identification algorithm based on artificial fish swarm algorithm which could be adaptive dynamically was developed.Compared with the original algorithm,the improved algorithm has a higher accuracy of parameter identification,and successfully realized the parameter identification of the magnetization curve of Sm2Co17 material.The post-assembly magnetization coil adopts the saddle-shaped structure,which has a high degree of coupling between the rotor and the coil.Compared with the triple-coil magnetization coil,the saddle-shaped structure reduces the total magnetic energy by 61%.In the process of magnetization,the straight edge of the coil will bear huge electromagnetic force.In order to ensure the stability of the coil structure and the rapid loading of the rotor,the internal support structure was designed and the stress levels in the structure were verified by the finite element simulation.The parameters of the post-assembly magnetization power supply system and the coil were optimized jointly.The shorter the pulse width of the magnetizing magnetic field is,the lower the power energy required by the magnetizing coil is and the lower the temperature rise of the coil is.However,under short pulse width,the eddy current effect in the coil structure and the sleeve of the rotor is strong,which affects the strength and direction of the magnetizing field.Therefore,the eddy current effect in the process of pulse magnetization was analyzed.Combined with the parameters of the coil and power supply,the pulse width and the energy of the magnetizing system were optimized.The winding process of the saddle-shaped coil was designed and the prototype was manufactured.Through the tests and experiments,the prototype successfully realized the post-assembly magnetization of the rotor and the actual test result of the rotor is consistent with the dynamic simulation of the J-A model.Under the same configuration of the power supply,the energy storage of capacitor bank pulse power supply is reduced to 230 k J,which is 50% of the triple-coil structure’s storage. |
