Research On Dual-three Phase Permanent Magnet In-wheel Motor And Analysis Of Fault Tolerant Performance

In-wheel motor direct drive system has the performance advantages of simple mechanical structure,high transmission efficiency,flexible control,easy integration design and other drive methods,becoming an inevitable trend of electric vehicle drive system technology development,It is one of the key and hot technologies in the research of electric vehicles at home and abroad.The reliability and safety of wheel hub motor drive systems are important indicators of the performance of electric vehicles.The dual three-phase permanent magnet in-wheel motor studied in this paper not only possesses the remarkable advantages of high efficiency and energy saving,high power density of the permanent magnet motor,but also has the characteristics of high fault tolerance of the multi-phase motor,and is very suitable for the electric vehicle drive.The article first studied and designed a 20-pole 24-slot ordinary three-phase permanent-magnetic in-wheel motor with fractional-slot winding and surface-mounted external rotor structure.The DesignXplorer tool was used to optimize the initial scheme of the motor,and finally the electromagnetic scheme of the motor was determined.The finite element simulation analysis was carried out using Maxwell software,and the basic performance curve and efficiency map of the motor under no-load and full-load conditions were obtained.In view of the large cogging torque of the motor,this paper proposes the use of cosinusoidal non-uniform air gap and magnetic pole offset methods to achieve the purpose of weakening the cogging torque,thus,the torque ripple under full load conditions is controlled within a reasonable range;Secondly,the article deduces the mathematical model of the two-phase three-phase motor in the natural coordinate system and double D-Q axis coordinate system,and re-arranges the stator winding on the basis of the common three-phase winding,two dual three-phase winding schemes with double Y phase shift 30° and double Y phase shift 180° are obtained,the differences and similarities of the two schemes are analyzed in detail from the aspects of slot dynamic star diagram,winding coefficient,winding coupling,no-load back EMF and output torque;Then the article describes the fault-tolerance mechanism of two-phase three-phase motors and simulates the electromagnetic performance of two dual three-phase winding schemes under single-phase and three-phase fault conditions,focused on the comparison of output torque performance after motor failure.Finally,the paper summarizes the full text and prospects the application prospects of dual three-phase permanent magnet wheel hub motor in the electric vehicle drive system.It points out that the article still needs further research content and direction.