Research On Control Strategy Of Five-Phase Permanent Magnet Fault-Tolerant Motor Starter/Generator System

In the design of traditional electric transpot tools,the engine starter system and the power generator system are generally independent of each other.The starter system is only responsible for starting the engine and it will stop after completing the starting process,which becomes an additional load for the vehicle.According to the reversible working principle of electric machines,starter / generator system first operates in the electric mode to start the engine,and then it switches to the generation mode for power supply.By reducing the weight and cost of electric transpot tools,this system topology has become the technology development trend.Meanwhile,due to the advantages of high power density,high torque density and high efficiency,polyphase permanent magnet fault-tolerant motors have become the preferred solution for starter/ generation systems.In this thesis,a starter/ generator system of five-phase permanent magnet fault-tolerant motor is taken as the research object,and its control strategy is studied in detail.Firstly,the research background and significance of the subject are explained,and the current status of domestic and foreign research on starter / generator systems is introduced.Based on the three-phase permanent magnet synchronous motor,the structural characteristics and working principle of the five-phase permanent magnet fault-tolerant motor are analyzed,and a mathematical model of the five-phase permanent magnet fault-tolerant motor in the natural coordinate system is established.According to the transformation matrix of the five-phase motor,the mathematical model of the stator coordinate system and the rotor coordinate system is established.Secondly,a variety of topological structures of power converters are studied,and a highly reliable Hbridge topology is selected.Based on this,a control strategy for the five-phase permanent magnet faulttolerant motor system is analyzed.After that,the working principles of the starter system and the power generation system are analyzed respectively,and a combined control strategy is proposed to control the fivephase permanent magnet fault-tolerant motor starter / generator system.The derivation calculation and simulation analysis of SVPWM and hysteresis modulation algorithms in vector control system have been carried out.By comprehensively comparing the modulation effect and the complexity of the algorithm,and considering the convenience of fault-tolerant control,a variable duty ratio hysteresis modulation method is proposed.Thirdly,the analysis and calculation of the compensation current vectors of the five-phase permanent magnet fault-tolerant motor control system under several common open-circuit faults are completed with the minimum stator copper loss and the constant air gap magnetomotive force before and after the motor failure as constraints.Simulation verifies the feasibility of the fault-tolerant algorithm.Finally,according to the control strategy requirements and the actual conditions of the laboratory,a set of hardware controllers based on the TMS320F28335 DSP chip as the main control unit is developed,and the construction of the experimental platform is completed on this basis.Meanwhile,using CCS9.0.0software as the development environment,the motor control strategy and fault tolerance algorithm as the theoretical basis,the C language-based motor control program is completed,and the five-phase permanent magnet fault-tolerant starter / generator system control strategy is experimentally analyzed to verify the feasibility and effectiveness of the control strategy.