Multi-physics Analysis And Design Of A Novel Five-phase Permanent Magnet Synchronous Motor For Electric Vehicles

Multiphase motors have received widely attention in the academia because of their advantages of low torque ripple,high reliability,high fault tolerance and high power density.Especially in recent years,as the rapid development of power electronics technology and control theory,the multi-phase motor's disadvantage of complex control has transformed into its advantage of more control freedom,which broadened its application fields.Compared with the traditional integer slot winding,the fractional slot concentrated winding(FSCW)has a shorter ending winding and lower copper loss,and it also reduces the processing cost,which is widely used in the field of motor of electric vehicles(EV)application.In this thesis,the motor that used in EV is set as background,and a new five-phase permanent magnet synchronous motor with the FSCW is taken as the object of research.The following research is done:the slot/pole combinations of winding,design of stator and rotor based on multi-physics analysis:Firstly,the factors of influencing on the chosen of slot/pole combinations of five-phase FSCW are studied.Unlike three-phase motors,five-phase motors can generate a higher torque through the third harmonic current injection.Using the winding function method,a general mathematical model of the FSCW is built.Based on the model,the maximum winding factor is taken as the objective,and the winding arrangement of five-phase motor with any slot/pole combination is given.The fundamental and third harmonic winding factors,the magnetomotive force harmonic distribution,the torque ripple and the order of radial force are analyzed by using different slot/pole combinations.And the voltage phasor diagram method and finite element method are used to verify the above calculation.Secondly,based on the study of FSCW,the selection principle of slot/pole combination of five-phase bi-harmonic permanent magnet motor for EV is analyzed.Firstly,the chosen principle of slot/pole number of the motor is proposed.The characteristic of the different permanent magnet rotor structures are compared,and the rotor structure which suit for the five-phase bi-harmonic motor is determined.Then,the influence of slotting between the poles on the rotor is analyzed.Taking the root mean square value and peak value of the injected current in the winding as the constraint conditions,as well as the maximum torque of the motor as the objective,the applicability of the slotting design to the two different slot/pole number matching windings is compared.And the relationship between the rotor slot spacing and the motor size structure is studied.Finally,the finite element method is used to verify the advantages of rotor slotting on the performance improvement of the motor and the feature of bi-harmonic.Thirdly,according to the experimental conditions,a prototype of five-phase bi-harmonic permanent magnet motor is designed by using multi-physical analysis.Firstly,the main sizes of the motor are calculated.Then the initial design is verified and adjusted by multi-physical analysis:electromagnetic field,temperature field and stress field.Finally,the relevant analysis and design are verified by experiments.Finally,the content of the full-text research is summarized,and the future prospects of the research on machine are presented.