Design And Reliability Research Of Vehicle Motor Drive System

As the power core of electric vehicle,motor drive system greatly affects the power performance and reliability of electric vehicle.Vehicle environment is complex,and the reliability of motor drive system is very high.Based on an electric vehicle project,this paper designs and matches the motor drive system,carries out reliability analysis and research on the system,and optimizes the design of software and hardware for the key characteristics of reliability.The main research work of this paper is as follows:Firstly,this paper establishes the mathematical model of permanent magnet synchronous motor,compares and analyses the control methods of permanent magnet synchronous motor,and studies the vector control and pulse width modulation technology.Aiming at the research demand of motor drive system reliability,reliability index and analysis method are studied.According to the system requirements of the project electric vehicle,the power parameters of the motor drive system are matched.Secondly,this paper completes the hardware and software design of the motor drive system.According to the basic principle of motor drive system,the principle block diagram of the whole system hardware is designed and completed.Based on the chip of TMS320F28035,the components selection and circuit design of main control unit,detection circuit,inverter and drive,communication circuit and auxiliary power module are completed by modules.Based on the basic principle of vector control method,the field orientation control algorithm,space vector pulse width modulation and A/D interrupt program design are completed.Then,the reliability of motor drive system is studied.Combining FMEA with FTA analysis,the fault tree of each module and component failure form are established to complete the qualitative analysis of the reliability of motor drive system;the predicted failure rate of each module and the whole system is calculated by stress analysis method,combining with component reliability manual,and the predicted failure rate tables of each module are established to complete the quantitative calculation of system reliability;and the predicted failure rate is combined with the predicted failure rate.In order to improve the reliability of the system,the short board module is used.The parallel technology of MOSFET is simulated by Multisim,and the improved design of power board is completed.The fault-tolerant vector control of position sensor failure is simulated by MATLAB,which proves the correctness and feasibility of the faulttolerant scheme.Finally,the motor drive system designed in this paper is tested on the bench and on-board.Through bench test and verification,the motor drive system meets the requirements of various national standards;combined with the project,loading test is carried out.The road test results show that the motor drive system designed has high efficiency,stable control and good reliability,and meets the requirements of the vehicle project.