Fault Analysis And Fault-tolerant Control Of Four Phase Doubly Salient Electro-magnetic Machine System

Doubly salient electro-magnetic machine(DSEM)has the advantage of simple structure and good fault tolerant performance.What's more,the control of DSEM is flexible in electric mode,while the voltage regulation is convenient in power generation mode.Thus,DSEM has promising application prospect in aero-starter-generator field.Meanwhile,aerospace occasion has high reliability requirments.Machine system faults can lead to disastrous results.As a result,the fault tolerant control of DSEM system is of vital importance.Firstly,the structure,mathematic model and the electric operation principles of four-phase 24/18-pole DSEM is introduced in this thesis.A fault-tolerant drive system topology with two bilateral switch is presented.The four phases of the DSEM are connected in two channels.Based on the presented drive system,different fault types are analysed and the corresponding fault tolerant control strategies are carried out.What's more,for one-phase open-circuit fault,fault-tolerant current amplitudes of the rest three phases,which make the copper loss least,are calculated.The dynamic models of normal operation and one-phase open-circuit fault tolerant operation are deduced.Secondly,field-circuit coupling simulations of four-phase DSEM finite element model and the drive circuit model are carried out to analyse the output torque in different operation situations,including normal operation,fault operation and fault-tolerant operation.Simulation results indicate that fault-tolerant control can improve output torque and reduce torque ripple.For one-phase open-circuit fault,output torque in different fault-tolerant current amplitudes are simulated.Considering output torque,torque ripple and copper loss,optimal fault-tolerant current amplitudes are found.Lastly,the four-phase DSEM fault-tolerant drive system hardware experimental platform are designed and built.The system software are also designed to carry out experiments of different operation situations.For one-phase open-circuit fault,experiment results verifies the reduction of the normal operation and fault-tolerant operation model.Under loading circumstances,derating fault tolerant experiments are carried out.Starting experiments of normal operation,fault operation and fault-tolerant operation are also conducted.All the experiment results prove the feasiblity and validity of the fault-tolerant topology and fault-tolerant control strategy.