Research On Eddy Current Loss,Temperature Rise And Electrical Force In High-Speed Induction Motor With Composite Rotor

The high-speed induction motor with composite rotor not only has the squirrel cage rotor structure,but also uses the solid rotor structure.The distribution of magnetic field in rotor is more complex,which makes it difficult to accurately calculate the eddy current losses in rotor.Compared with the common induction motor,high-speed induction motor with composite rotor produces large eddy current and eddy current losses in solid rotor,resulting in high temperature rise and large electrical force in motor.A 1500kW high-speed induction motor with composite rotor is taken as the research object,the calculation method of eddy current losses in solid rotor,the calculation of 3D global temperature field and distribution law of electrical force in rotor and stator winding are studied and analyzed.Based on the magnetic field of the rotor surface.according to the Maxwell’s equations and the law of energy conservation,the semi-analytical algorithm for the eddy current losses in solid rotor of high-speed induction motor with composite rotor is derived.The calculation results obtained by 2D eddy-current finite element method are substituted into the semi-analytical algorithm to calculate the eddy current losses in solid rotor of high-speed induction motor with composite rotor under different working conditions.The accuracy of the semi-analytical algorithm is verified by comparing the results of the semi-analytical algorithm and the 2D transient finite element method.Considering the influence of cooling air on the temperature distribution in motor,a physical model of the coupling 3D temperature field and fluid field in high-speed induction motor with composite rotor is established.The various losses in motor obtained by the 2D transient finite element method are used as the heat source,according to the finite volume method to calculate the temperature distribution of each structure in motor,and the distribution law of the temperature in high-speed induction motor with composite rotor is studied.A 3D physical model of the high-speed induction motor with composite rotor is established to calculate the flux density and the electrical force density in different areas of high-speed induction motor with composite rotor.According to the coordinate transformation,the electrical force density in different directions of rotor and stator winding are transformed into the radial,tangential and axial electrical force density,the distribution law of electrical force density in rotor and stator winding is analyzed.