Research On Modular Five-phase Fault-tolerant Permanent Magnet Synchronous Motor For Pure Electric Vehicle

Since 21 st Century,the increasingly serious environmental pollution and energy crisis have become the main factors that restrict the development of human beings.A series of problems such as environmental pollution and energy waste caused by traditional fuel automobiles cannot be ignored.It is urgent to develop new energy vehicles.For new energy vehicles,the pure electric vehicle is widely concerned because of the advantages of zero emission and zero pollution.For electric vehicles,the reliability and fault tolerance of the motor and its control system are the key assessment indicators,which are related to vehicle and personnel safety.Compared with the traditional three-phase permanent-magnet synchronous motor(PMSM),the faulttolerant operation ability of the multi-phase PMSM is greatly improved,and it has the advantages of high power density and high efficiency.Therefore,the multi-phase PMSM is an ideal choice for the electric motor system of the pure electric vehicle.This paper focuses on the structure characteristics,optimal design and fault-tolerance control of five-phase PMSM Based on hybrid single-/double-layer fractional-slot concentrated winding(FSCW).The major work can be follows:Firstly,the hybrid single-/double-layer FSCW scheme is studied.Combined with the application background of pure electric vehicle,this paper analyzes the requirement of modular multi-phase PMSM for stator modularization,and puts forward a hybrid single-/double-layer FSCW on the basis of the study of the double layer FSCW.The high magnetic isolation performance and modular design feasibility of the scheme are verified,and compared with the single-layer and the two-layer FSCW scheme.Secondly,the modular five-phase fault-tolerant PMSM is optimized.For the stator structure,aiming at the special structure of the modular five-phase fault-tolerant PMSM,the matching principle of the pole and the slot is proposed.In order to improve the winding factor,the mechanical angle between the single-layer-winding slot and the double-layer-winding slot is optimized,in order to suppress the end short current and improve the electromagnetic performance,the slot-opening width of the single-layerwinding slot and double-layer-winding slot is optimized.For the rotor structure,the influence of the polar arc coefficient on various electromagnetic properties is studied,and the best arc coefficient is selected.To reduce the eddy current loss and improve the efficiency of the motor and the permanent magnets are divided into two blocks.Thirdly,the fault tolerant control strategy of modular five compatible permanent magnet synchronous motor(PMSM)under open circuit fault is proposed.Combined with the application background of pure electric vehicle,three cases of open circuit which is one-phase open,two-adjacent-phase open and two-separated-phase open are discussed,The torque output characteristics of two fault tolerant control strategies are analyzed by finite element simulation.At last,the equivalent circuit model of inter turn short circuit is established for inter-turn short circuit fault,and the inductance parameters of short circuit winding and remaining winding are calculated by magnetic circuit method,and the short circuit winding current is calculated.To verify the validity of the method,the result is compared with the one calculated by finite element method(FEM).The torque output characteristics of different inter-turn short-circuit faults are studied by finite element simulation.