Research On Design And Fault-tolerant Operation Of Six-phase Fault-tolerant Permanent Magnet Machine

Fault-tolerant permanent magnet synchronous machine(PMSM)with significant advantages including simple structure,high reliability,power density and fault-tolerant capacity has been widely used in defense-related technology,ship propulsion and electric vehicle applications.The machine design and operation strategy are the key to the fault-tolerant capacity of the system.In order to improve the reliability of the drivetrain in military vehicles,this thesis studies the design and fault-tolerant operation strategies on winding faults of six-phase fault-tolerant PMSM.Firstly,based on the design principles of fault-tolerant PMSM,the electromagnetic scheme selection including number of phases,slots and poles combinations,windings and rotor structure is investigated.A symmetrical six-phase fractional-slot concentrated winding fault-tolerant PMSM with half bridge and neutral line topology is proposed.The performance of the prototype is verified by the finite element method(FEM),which shows that the prototype meets the requirements of good electromagnetic performance and fault-tolerant capacity.In order to find the electromechanical-energy-conversion relationship in phase,the mathematical model of the six-phase fault-tolerant PMSM in the natural coordinate system is established and the torque equation is deduced and analyzed based on the virtual displacement method.The impact of the third harmonic flux linkage on machine operation is emphatically analyzed.All above works lay the foundation for the torque pulsation analysis and research on fault-tolerant operation.Then the fault-tolerant operation of the machine for winding open-circuit and short-circuit faults are studied.The magnetomotive force(MMF)and torque under winding faults and the influence of faults on the machine are analyzed and summarized.According to the torque equation of fault-tolerant machine under winding faults,a fault-tolerant operation strategy based on the principle of minimum torque ripple is proposed and the fault-tolerant excitations are computed.Finally,the fault-tolerant operation strategies are verified by FEM.It is shown that torque pulsation can be significantly reduced while meets the output demand.