Research On 3-phase Modular Fault-tolerant Permanent-magnet Motor

Distributed drive electric vehicle has become the focus of research in recent years because of its good acceleration and control,as the core components,electric motor system's reliability is of the most important.In order to improve the faults tolerant capability of hub motor system,and to solve the problems of complex structure and difficult control algorithm of traditional fault-tolerant motor,a modular fault tolerant hub motor is proposed in this pape r.Several key technical problems of modular fault-tolerant hub motor are mainly discussed:Firstly,considering the special structural characteristics of the three-phase modular fault-tolerant hub motor,the mathematical model and the working principle of the motor are studied.The flux linkage equation and voltage equation of modular fault tolerant hub motor are deduced with all modules running and some modules running.The form of self-inductance and mutual inductance of modular fault-tolerant permanent magnet motor are discussed.Secondly,the electromagnetic scheme of modular fault-tolerant permanent magnet motor is analyzed,and the selection method of modular motor electromagnetic scheme is given.The motor performance is greatly affected when the short-circuit fault happens,so the winding short-circuit is studied by using analytical method and finite element simulation.After determining the scheme of stator motor,various magnetic structure of the rotor is analyzed,the motor torque ripple is optimized by using the method of permanent magnet eccentricity.Thirdly,the fault tolerant strategy of motor under different fault conditions is studied considering the characteristics of modular fault tolerant motor.A fault-tolerant control strategy for one phase open circuit fault is proposed,which gets rid of the problem that the current of the fault module is too large when the constant armature magnetomotive force strategy is applied.The problem of unbalanced magnetic force and torque ripple during one phase open fault tolerance is analyzed,and some countermeasures are given.The operation characteristics of several modules are analyzed,and the methods of restraining torque fluctuation are given.Fault tolerance strategy after winding short circuit faul t of modular fault tolerant permanent magnet motor is proposed.The problem of winding overheating and torque ripple caused by short circuit fault is solved.The inter turn short circuit fault between two strands is studied according to the actual situatio n,and the methods of restraining this fault current is given.Finally,a 3 dimensional temperature field model is established for different fault conditions of modular fault-tolerant hub motor,and the temperature rise of the motor under normal and fault tolerant conditions is analyzed to ensure the stable operation of the motor under normal or fault-tolerant conditions.