Electromagnetic Analysis And Design For High Speed Composite Solid-Rotor Induction Motor

Composite solid-rotor induction motor(CSRIM)has many advantages,such as simple manufacture,low cost,high mechanical strength,high speed adaptability,and etc.It has broad application prospects in the field of high speed direct drive.However,because of the solid-core structure,the electric field and magnetic field on the rotor are mixed together,which brings some difficulties to mathematical modeling and optimization design.At the same time,due to the high loss density,small heat dissipation area and relatively serious rotor heating,the analysis of rotor eddy current loss is the key point of optimum design of solid rotor induction motor.In this paper,the mathematical model and electromagnetic field analysis of high-speed CSRIM are carried out,and the eddy-current loss of the rotor is analyzed emphatically,and the optimization design is carried out based on the established mathematical model.The details are as follows:Firstly,considering the coupling of electric field and magnetic field on the side of solid rotor,the traditional magnetic circuit calculation method can not be applied to the design of CSRIM.Therefore,a simplified mathematical model of CSRIM is established,which ignores the cogging effect.Based on the method of combining field and circuit,the performance of the motor with multiple constraints is analyzed in the impedance plane of the rotor.Secondly,considering that the rotor loss of high-speed CSRIM contains a large number of high-frequency eddy-current components,and the simplified mathematical model can not calculate the rotor eddy-current loss except the loss of fundamental current,the electromagnetic analytical model of CSRIM considering stator slotting is established.Based on the above model,the effects of stator slot number,winding span,air gap width and composite layer thickness on rotor eddy current loss are analyzed,and the temperature-rise test caused by rotor eddy current is designed to verify the accuracy of the mathematical model,which provides a basis for the optimization design of high-speed CSRIM.Finally,considering that the electromagnetic optimization design of CSRIM is a complex problem with multi-variables and multi-constraints,the traditional method can not be used for global optimization design.Therefore,it is necessary to select an appropriate and efficient optimization algorithm.In this paper,a 9kW,50000 rpm target prototype is optimized based on the above-mentioned mathematical model of CSRIM and genetic algorithm,and the statistical rules of the optimized sample population are analyzed.