The Fault-tolerant Technology Of Six-Phase Double-Y 30°-Deflected Permanent Magnet Synchronous Motor

With the advantage of high power density and high efficiency, multi-phasepermanent motor has been widely used in the field of industrial and agriculturalproduction, aerospace and national defense. It is required to be high reliability due toits special applications. Therefore, fault-tolerant motor and control system has beengiven more and more attention.Taking multi-phase permanent magnet synchronous motor as research object,this paper discusses the classification, structure and characteristic of multi-phasepermanent magnet synchronous motor and introduces in detail the definition of phase.Based on the mathematical model of six-phase double-Y 30°-deflectedpermanent magnet synchronous motor, through analyzing magnetomotive force, thispaper discusses fault-tolerant strategies for various off-phase, including single-phase,two-phase and three-phase off-phase respectively, in motor with and without neutralline. According to the vector control principle of permanent magnet motor, in rotorflux orientation coordinate system, torque current is on q axis while filed current is ond axis. In fault-tolerant controlling, if the positive phase sequence magnetomotiveforce of the left combination current is on q axis and the negative phase sequencemagnetomotive force is zero, the torque will be developed at maximum efficiency.This paper also presents the action graphic of magnetomofive force in fault-tolerantcontrolling based on the mathematical expression of each phase.This paper also establishes six-phase permanent magnet synchronous motor inMATLAB/Simulink, through simulation analysis on fault-tolerant controlling strategyof each off-phase in the two situations, compares the phase current and torque beforeand after fault-tolerant controlling, obtains a good effect.