Design And Open-circuit Fault-tolerant Control Of Five-phase Permanent Magnet Synchronous Motor With Surface-mounted External Rotor

In the context of major national development projects such as aerospace,deep-sea exploration and new energy vehicles,there are increasing requirements on high torque density and good fault-tolerance of a permanent magnet synchronous motor(PMSM).Under this background,many favorable merits of multi-phase PMSM show up and attracting more and more scholars at home and abroad devote into the study of structural design,speed control system as well as fault-tolerant scheme.This thesis will take a five-phase PMSM as researching object,designing a motor with non-sinusoidal distribution stator windings so as to improve its torque density.Based on the design motor,the speed control system and single-phase open circuit fault-tolerant strategy of five-phase PMSM with injected third harmonic current will be discussed.Firstly,the design and modeling of multi-phase motor and fault-tolerant control theory are systematically summarized,besides the research history and current situation of multi-phase motor are summarized.Then,the mathematical models of five-phase PMSM under normal and single-phase open circuit fault are built in natural coordinate system.The transformation matrices Clark and Park from natural to synchronous rotating coordinate system of five-phase motor are derived from three-phase motor,and the five-phase PMSM mathematical models is transformed from natural to synchronous rotating coordinate system so as to realize the decoupled control of d-and q-axes.The main work and researching achievements of this thesis contain following three aspects:1.Take high torque density as the goal,a 30 slots 32 poles surface-mounted outer rotor five-phase PMSM is designed.Three different winding modes are studied and compared on the air gap flux density,back EMF and mutual inductance.Finally a double winding structure is selected.Considering both the increase of loss and torque density,the optimal third harmonic injection rate is studied.2.The space vector modulation method(SVPWM)for five-phase PMSM is studied.Firstly,two methods for five-phase PMSM with sinusoidal winding distribution are derived,which are Near Two Vectors SVPWM and Near Four Vectors SVPWM.Then,a four-dimensional SVPWM method which is suitable for five-phase PMSM with non-sinusoidal winding distribution is proposed so that the fundamental and third harmonic components will be taken into account both.3.A single-phase open circuit fault-tolerant control(FTC)strategy considering the third harmonics is studied.Based on the criterion of unchanged fundamental and third harmonic magnetomotive force(MMF),the postfault phase current expressions are obtained and processing the order reduce of transformation matrices.A fault-tolerant strategy is proposed,which only changes the coordinate transformation matrix before and after the fault,but does not change the control mode.The motor design is realized in Maxwell/Ansoft software and verifying its inductance and electromagnetic torque by finite element analysis.The proposed third harmonic injection rate,four-dimensional SVPWM and fault-tolerant strategy are simulated in MATLAB/Simulink.The RT-LAB and dSPACE platform verify the effectiveness of these methods.