Calculation And Analysis Of Starting And Running Performance Of Composite Solid Rotor Permanent Magnet Synchronous Motor

Line-Start Permanent Magnet Synchronous Motor(LSPMSM)has not only the self-starting ability of IM,but also the advantages of high power density,small size and high efficiency of PMSM.It is suitable for frequent start-up places and in line with the current trend of energy saving and emission reduction.LSPMSM can be divided into Squirrel-Cage Rotor LSPMSM and Solid Rotor LSPMSM.In this paper,equivalent parameters of the rotor side,dynamic starting model,starting performance,loss reduction and heat dissipation channel design of Composite Solid Rotor LSPMSM which is derivative structure of solid rotor type,are studied.Firstly,the paper studies calculating method and influencing factors of Composite Solid Rotor LSPMSM starting performance.Since the electromagnetic transient process is much faster than the electromechanical transient process,the starting process can be decomposed into steady-state asynchronous operation at different speeds.Aiming at the asymmetry of rotor magnetic circuit caused by permanent magnet,the equivalent circuits of d-axis and q-axis are established respectively.The vector form of stator side parameters and excitation parameters can be obtained by sorting out the finite element calculation results.The rotor side parameters at different rotational speeds can be obtained by solving the dynamic equation of the motor,and the dynamic rotor parameters curve at starting can be obtained.Based on the motor voltage equation,flux equation,torque equation and other dynamic equations,the starting calculation model of Composite Solid Rotor LSPMSM with dynamic rotor parameters is established.The effects of squirrel cage guide bar and slotting on rotor parameters are studied.The starting and pulling synchronization abilities of LSPMSM with different structures are compared.From the angle of rotor parameters,the reasons why squirrel-cage can improve the starting ability and pulling synchronization ability of motor and why slotting can enhance the pulling synchronization ability of motor are explained.Secondly,the paper studies steady-state operation loss and loss weaken measures of Composite Solid Rotor LSPMSM.Stator slotting can cause teeth harmonics,affect air-gap magnetic flux density and inductive electromotive force,and produce rotor eddy current loss.The effects of three methods on the reduction of eddy current loss on the rotor surface are studied,which are increasing the length of air gap,using non-uniform air gap structure and using magnetic slot wedge.Increasing the length of air gap will reduce the degree of non-uniformity of air gap permeability,weaken the teeth harmonic magnetic flux density and reduce the eddy current loss of rotor.But it will reduce the starting torque and power factor of motor.The non-uniform air-gap structure can improve the waveform of air-gap magnetic density,reduce the influence of teeth harmonics on air-gap magnetic flux density and EMF,effectively reduce the eddy current loss of the rotor,and have less influence on the starting torque and power factor.The magnetic slot wedge can increase the leakage between stator teeth,reduce the teeth harmonic magnetic flux density in air-gap and the eddy current loss.But high permeability of the slot wedge will lead to excessive leakage and affect the starting performance of the motor.Combined the above three methods,it can be found that by using 12.5/7.5 non-uniform air gap structure and magnetic slot wedge with relative permeability to be 7,the motor loss can be minimized and the starting and steady-state performance of the motor can be guaranteed.Thirdly,in order to prevent the permanent magnet from irreversible demagnetization,accelerating insulation aging and affect to the safe operation of the motor,the paper studies the temperature rise of the motor,and designs the ventilation and heat dissipation system of the motor.The air gap between stator and rotor is small and the air flow is complex,the heat dissipation of rotor is difficult,which will lead to higher temperature rise.Permanent magnet will face the danger of irreversible demagnetization.The thermal conductivity of external insulation of stator winding is poor,and the aging speed of insulation material will be accelerated when the temperature of stator winding rises.Using Ansoft-Fluent joint simulation,a fluid-temperature coupling solution model is established,and the temperature rise distribution in the motor is obtained.The rotor axial ventilation duct is designed to reduce the temperature rise of permanent magnet.The heat dissipation effect of different size and position of the rotor heat dissipation channel is studied.At the same time,the starting torque and power factor of the motor change little.To ensure the insulation life of motor windings,the stator radial heat dissipation channel is designed,and the heat dissipation effect of different intervals of stator ventilation ducts is studied.Finally,a 6-pole,10 kV,355 kW LSPMSM prototype is manufactured.No-load test,stop-up test,load test and temperature rise test were carried out.The measured motor loss and temperature are compared with the results of finite element simulation and Fluent simulation.