Research On Vector Control System Of Flux-modulation Permanent-magnet Fault-tolerant Machine

Flux-modulation permanent-magnet(FMPM)fault-tolerant machine is a new class of permanent-magnet fault-tolerant machine which works based on the flux-modulation principle.It combines the merits of high torque density of flux-modulation machine with high reliability of permanent-magnet fault-tolerant machine,thus having a certain range of applications in the field of high torque density and high reliability.In this thesis,a five-phase FMPM fault-tolerant machine is taken as the research object.Vector control system and fault-tolerant control strategy of the machine are researched.Moveover,an improved five-phase space vector pulse width modulation(Space Vector Pulse Width Modulation,SVPWM)fault-tolerant control method is proposed.Finally,correctness of the theoretical analysis is verified by the simulation and experiment.The main research contents of this thesis are as follows:1? Structure feature,flux-modulation principle and static characteristics of the FMPM fault-tolerant machine are analyzed.Its mathematical models and voltage matrices are deduced based on three different coordinate systems.Besides,relationships of coordinate transformation among models are explained and deduced in detail which lay a foundation for the following vector control researches under normal and single-phase open-circuit fault-tolerant conditions.2? Based on SVPWM control strategy for normal operation,the characterisis of the machine in base speed and flux-weakening regions are studied.In the base speed region,id = 0 control strategy is used.Also,as for the flux-weakening region,a kind of flux-weakening control strategy is adopted,in which the moment of flux-weakening is judged based on the difference between DC-bus voltage and back electromagnetic forces.Last,the correctness of the SVPWM control strategy for normal condition is verified.by parameter calculation and Matlab/Simulink simulation results.3? A general five-phase SVPWM fault-tolerant control theory of the FMPM fault-tolerant machine is deduced and analyzed based on single-phase open-circuit fault.Then,an improved SVPWM fault-tolerant control approach is proposed,which is derived from the proposed fault-tolerant control theory.Compared with the traditional SVPWM fault-tolerant control,the improved SVPWM fault-tolerant approach can offer increased DC-bus voltage utilization and reduced current harmonics,Correctness of the improved fault-tolerant control approach is demonstrated by theoretical and simulation analysis results.4? An experimental platform based on digital signal processing for FMPM fault-tolerant machine is established.Also,its hardware and software system including drive circuit and control program are designed.Normal experimental tests on a prototyped FMPM fault-tolerant machine are carried out in both the base speed and flux-weakening regions.Then,fault-tolerant operation experimental tests are developed under single-phase open-circuit condition.Thus,the effectiveness and enforceability of the five-phase SVPWM vector control strategy for the FMPM fault-tolerant machine are demonstrated.