Loss Characteristics And Its Reduction Measures Of High Speed Cage Solid Rotor Induction Motor

High-speed motors can be directly connected with load,which not only reduce the volume of the system but also improves its reliability,and it is widely used in machine tool spindle,air compressor and other industrial fields.The solid rotor induction motor owns the characteristics of simple structure and high mechanical strength,with unique advantages in the above fields.However,due to the influence of complex air gap harmonics,the skin effect on the surface of solid rotor is serious,which leads to the over concentration of local magnetic and electric density.The eddy current loss of rotor accounts for the main component of the loss,thus affecting the temperature rise of normal operation of the motor.In order to propose effective measures to reduce its loss,the loss characteristics of high-speed solid rotor motor and the improvement scheme of rotor structure is proposed.The main contents are as follows:1)Taking 160kW and 3MW induction motors as examples,preliminary electromagnetic schemes by using steel sheet rotor is designed with magnetic circuit method.Furthermore,time-step finite element method is used to analyze the loss characteristics by steel sheet and solid rotor respectively.2)Copper loss and eddy current loss of solid rotor induction motor are systematically studied with the variation of air gap length,slot combination,rotor conductivity and other key electromagnetic design parameters.Influence of fundamental and harmonic electromagnetic quantities on eddy current loss of solid rotor is revealed,and the key parameters are optimized and improved to reduce the loss of solid rotor.3)Three-dimensional finite element method is used to compare the distribution characteristics of electromagnetic quantity on the rotor side before and after the improvement,which verifies the effectiveness of the electromagnetic quantity optimization measures mentioned above;Furthermore,the eddy current distribution characteristics of the solid rotor with radial and axial grooves on the rotor surface are compared.A 160kW prototype is manufactured,and the effectiveness of the improved design scheme is verified by experimental research.