Design And Analysis Of Fractional Slot Concentrated Winding Interior Permanent Magnet Synchronous Motor For Electric Vehicle Applications

The fractional slot concentrated winding interior permanent magnet machines(FSCW IPMs)have the merits of low copper loss,good flux-weakening speed-enlarged(FWSE)capability and good fault tolerance,making them good candidates in the appilication of electric vehicle(EV).However,FSCW motors contain abundant harmonic components owing to therir inherent winding characteristics,which are the main cause of the increasing iron losses,torque ripple and voltage harmonics,thus affecting the motor efficiency and the constant power speed range(CPSR).The thesis compares the inductances,saliency,losses,efficiency and FWSE capability of the FSCW IPMs with different pole-slot combination for EV applicatrion.A 12-slot-8-pole IPM with deltatype connection is designed,optimized and prototyped to verify the validation of the theory and finite-element-method(FEM)simulation of the motor.Firstly,the d-axis inductance and the saliency of the FSCW IPM with different pole-slot combination is investigated at different load condition.The winding factors of FSCW motors are deduced based on the conductance wave.Combining the deduced winding factors and the d-and q-axis inductances derived with the magnetic circuit method and Park transformation with infinitely permeable iron,the d-and q-axis airgap inductance coefficient and slot leakage efficient is difined to represent the d-and q-axis inductance.The regulation for the d-aixs inductances and the saliency of the FSCW motors with different pole-slot combination is analyzed and revealed,which is validated using the finite element method.Then the regulation of the d-and q-axis inductances,and saliency of the motor under on-load condition is analyzed.Furthermore,the torque characteristics of FSCW motors under maximum-torque-per ampere(MTPA)control is investigated to compare the influence of pole-slot combination.Then,the output capability of the FSCW IPM under the constrain of the inverter is investigated.The voltage distortion coefficient is defined to represent the harmonic voltage.The flux weakening mathematic modle of the motor considering the harmonic voltage is built.The effect of the rotor magneto motive force(MMF),the stator MMF,the rotor saturation and the stator saturation on the voltage harmonics under different currents are investigated respectively with frozen permeability(FP)method.Therefore,the shape and the parameters of different magnet and its magnetic bridge are analyzed and compared to find out the appropriate design for lower voltage harmonics and wider CPSR.In addition,a non-uniform rotor air gap topology is proposed to effectively reduce the voltage harmonics of motor in flux-weakening area and increase the CPSR.After that,the motor performances of the FSCW IPMs with different pole-slot combimation,including losses,efficiency and vibration,are investigated.The iron losses,the permanent magnet eddy current loss,and the alternating current(AC)copper losses of FSCW IPM with different pole-slot combination are analyzed and compared.The influence of the current amplitude,and the power angle on the losses are specifically analyzed.For EV motors,the operation area is mainly diveded into two parts,one is the constant-torque area and the flux-weakening area.The current distribution of the two areas are analyzed,then the efficiency map is simulated and compared for12-slot-8-pole IPM,12-slot-10-pole IPM,and 12-slot-14-pole IPM.The vibration and antidemagnetization capability of the FSCW IPMs are analyzed.The comprehensive performances of the FSCW IPMs are compared for the guidance for EV motor application of the choice on the pole-slot combination.Finally,the 12-slot 8-pole IPM with delta-type connection is optimized,designed,prototyped and tested.It is optimized with genetic algorithm(GA)with the constration of the inverter aiming at the highest peak power and efficiency at the rated condition.A new rotor topology is proposed to reduce the torque ripple.The weight reduction holes are well designed to fulfill the restriction of the mechanical stress of the motor at 1.2 times of the maximus speed.The permanent magnet motor with peak power of 112 k W and maximum speed of 12000 r/min was prototyped,and the results of finite element simulation were verified through experiments.