Electromagnetic Design And Analysis Of Twelve-Phase Low-Speed Permanent Magnet Synchronous Motor

The main contents of this paper is to study the electromagnetic design and analysis of the multiphase permanent magnet motor.The multiphase permanent magnet motor has high power density,high efficiency,high reliability and high fault tolerance.It is widely used in aerospace,ship propulsion,electrical locomotives and other electrical drive system.It has received more and more attention.The research about the design and control strategy of multiphase permanent magnet motors has become a hot point of the motor disciplines,and the new direction of the motor field.Conjunction with the main performance requirements of the motor design,considering of characteristics of high power density,high reliability,low noise and vibration of the low-speed high-torque permanent magnet synchronous motor for submarine propulsion,this paper analyzed the impact of the performance of different motor stator windings and the combination of poles with slots.The 40poles-192 slots double-short distributed winding is selected,to reduce the harmonic content,vibration and noise.The entire motor can be seen as four 10poles-48 slots unit motors displaced in turn by 15°.It investigated the characteristic of electromotive force,magnetic motive force and electromagnetic torque,optimized it through changing the structure of the stator and rotor.The structure parameters were determined,the coefficient of electromotive force and magnetic motive force were acquired.It analyzed the characteristics of electromotive force generated by the fundamental and main harmonic current.On the basis of the analysis of electromotive force and magnetic motive force,it analyzed characteristics of the constant torque and 6,12,18,24 frequency multiplication electromagnetic torque.It summed up that when the motor is operating normally,there are the presence of a constant electromagnetic torque and 24,48,72,96,...frequency multiplication electromagnetic torque.According to the analysis results of permanent magnet MMF,it analyzed each harmonic content of gap magnetic field under different pole arc coefficient of the permanent magnet,then the appropriate pole arc coefficient was selected.Using the finite element analysis software,it investigated electromagnetic characteristics of the motor at no load and rated load conditions.It calculated the flux density of the air gap,no-load back-EMF motor parameters,then optimized the motor.It analyzed the characteristic of the cogging torque,and weaken it by skewing.The results show that the motor has good power index.It investigated the stator copper loss,iron losses,the eddy current loss of permanent magnet,and calculated losses by the finite element software.