Loss And Heat Analysis Of Large Power High Speed Squirrel-Cage Solid Rotor Induction Motor

Different from the ordinary induction motors,large power high-speed solid rotor induction motors need to solve the key problems such as small cooling area,large loss density and high temperature rise due to the compact structure,abundant voltage harmonics and high frequency.In this thesis,a 10 000 kW,10 000r/min squirrel-cage solid rotor induction motor is taken into account and the electromagnetic field,the high frequency loss and the temperature field of the motor running at the rated condition under sinusoidal fundamental wave and inverter supply situations are studied by finite element method.Firstly,the systematic simulation model of DHVECTOL-DI series cascade high voltage inverter is established.The amplitudes and distributions of fundamental and harmonics of inverter output voltage are obtained,which provides the relevant data for subsequent analysis and calculation of loss and temperature rise of the motor.Secondly,a 2D nonlinear field-circuit coupled parameterized finite element model of electromagnetic field is analyzed and established,and the main electromagnetic performances of the motor running at the rated condition supplied by sinusoidal fundamental and inverter respectively are analyzed and calculated.Thirdly,the stator high frequency copper loss and iron loss,the copper loss of squirrel cage,eddy current loss of solid rotor and surface wind friction loss of the motor under different supply conditions are analyzed and calculated.The corresponding calculation methods are proposed and the calculation results are obtained.And then,a 3D whole domain anisotropic parameterized finite element model of steady state temperature field is analyzed and built up.The temperature rise distribution of the motor is obtained.Finally,some factors which affect the temperature rise of the motor are analyzed and the improving suggestions for reducing the loss and temperature rise are proposed.The results show that the loss calculation of high-speed motors should consider the influence factors such as the high-frequency eddy current and higher harmonics comprehensively due to the large power,high speed,high frequency and solid rotor.The highest temperature of the motor appears at the axial middle section of the squirrel cage bar which is easy to exceed the material's long running limit temperature.Some improving suggestions,such as reducing the rated slip frequency and the roughness on the surface of the rotor,choosing the reasonable parameters of the inverter and cooling system,can be taken to keep the highest temperature at every component of the motor under the long running limit.The research results provide the references for the successful development of large power high-speed solid rotor induction motor.