Design And Analysis Of Features On Line-start Permanent Magnet Synchronous Motor

With damping winding in the rotor, Line-start Permanent Magnet SynchronousMotor (LSPMSM), which combines the advantages of squirrel cage induction motor fordirectly starting by coupling to an A.C. power and permanent magnet motor for hightorque and high energy index when running at synchronous speed, attracts more andmore attention in the motor research field in recent years.Generally, the permanent magnets are arc surface-mounted or rectangular straightinserted in the traditional LSPMSM rotor, for the former, it provides nice air gap fieldbut cuts down the motor starting capability, while the latter has good starting capabilitybut provides weaker electromagnetic characteristic.In this paper, to satisfy the production requirement, a LSPMSM is designed withthe arc straight inserted magnet, a new type of magnet which can provide good startingcapability and nice electromagnetic characteristic at meantime.Firstly, the structure of arc straight inserted LSPMSM, and the difference betweenthis structure and traditional structure are introduced. According to index parameters, a225M-822kW AI-LSPMSM is designed, electromagnetic parameters are obtained usingmagnetic circuit analytical method, and motor operation and starting performance areanalyzed.Secondly, on the base of magnetic circuit designing, key structure parameters,including air gap length, permanent magnet position, rotor slot height and magnetic fluxbarrier dimension of the motor, are optimized. Motor performance waveform changingwith parameter variation is got and the optimal parameters are determined.Afterwards, according to voltage equation and motor equation, motor startingprocess and steady-state operation characteristics are analyzed. Results show that motorwith new type rotor can start up quickly and has small steady-state current. Temperaturefield of motor operating on steady-state for4hours is calculated. It is verified thattemperature rise of new type motor is in normal range.Finally, a225M-822kW AI-LSPMSM prototype is made with the optimal result,good agreement between test results and design results demonstrated that the new structure motor indeed has good performance, and it can be used widely in industry.