Analysis And Design Of Low Harmonic Dual Three-phase Fractional Slot Permanent Magnet Synchronous Moto

Multi-phase permanent magnet synchronous motor(PMSM)combines the advantages of multi-phase motor and permanent magnet motor.It is more suitable for aerospace,nuclear power water-cooling,electric vehicles,naval submarines,etc.,which have higher requirements for motor reliability,power density,and smooth operation.It has far-reaching research significance and good application prospects.Therefore,in this paper,the dual three-phase PMSM,which is more commonly used in multiphase motors,is studied for low magnetomotive force(MMF)harmonic analysis and design research.There are many space harmonics in the stator MMF of fractional-slot concentrated winding(FSCW).These harmonics will produce high eddy current losses in the permanent magnet(PM).These harmonics also cause the problem of high torque ripple of the motor.Aiming at the above problems,in this paper,the design method of lowharmonic dual three-phase fractional-slot PMSM with two kinds of slot poles in the fractional slot is given.For Z=2p±2 slot pole combinations,taking the classic 10 pole12 slot motor as an example,the MMF harmonic analysis is carried out.Through the phase-band redistribution of the winding star diagram of the motor,the difference of each phase-band after splitting is 30 degrees,which can be designed as a dual threephase PMSM.Under this motor structure,the sub-harmonic in the stator MMF can be effectively weakened.For Z=2p±1 slot pole combinations,a novel space-shifted unequal-turn winding structure is proposed for dual three-phase fractional-slot PMSM.Meanwhile,the sub-and super-harmonics in the stator MMF can be simultaneously eliminated by selecting the appropriate phase shift angle between the two sets of windings and the ratio of the turns in each phase.Finally,using finite element simulation analysis,it is verified that the dual three-phase PMSM with new winding structure has low PM eddy current loss and torque ripple,which ensures the reliability and smoothness of motor operation.The air gap magnetic field generated by the surface-mounted PMSM with the traditional tile-type PM structure has a poor sine degree and high harmonic content,which leads to the problem of large torque ripple of the motor.In order to improve the air-gap magnetic field waveform and improve the performance of surface-mounted dual three-phase PMSM,a new design method of surface-mounted modulated PM structure is proposed.This method transforms the principle of specific harmonic elimination technology into the design of modulated PM.To calculate and solve the number,size,and position angle of the modulated magnetic poles,this method can realize the elimination and injection of specific harmonics of the air-gap magnetic field of the motor,so as to optimize the performance of the motor.The article uses its principle to solve the equivalent sinusoidal magnetic pole model and the third harmonic injection equivalent magnetic pole model.Then,finite element software is used to simulate the motor model equipped with three different rotor magnetic pole structures to verify the correctness and effectiveness of the new magnetic pole structure design method.