Hardware Design And Failure Analysis Of Synchronous Motor Driver

As environmental and energy issues become more prominent,many countries are committed to the development of the electric vehicle industry.As a motor drive component of electric vehicles,the research of motor drive controllers has received extensive attention.By summarizing the domestic and foreign research status of motor drivers and studying their control principles,the design scheme and research content of this thesis are determined,then a high-efficiency and energy-saving motor driver suitable for pure electric vehicles is designed and its reliability is analyzed.This thesis mainly analyzes the hardware from the power conversion main circuit,control circuit and drive circuit.In the main circuit of power conversion,the working principle of the inverter circuit is studied.And the influence of the bus capacitance on the voltage ripple and the ripple current flowing through the bus capacitance is analyzed;and pre-charging circuit with contactor and pre-charging resistor connected in parallel are designed for the problem of inrush current which formats at the moment of power on to practice the driver's reliability.In the control circuit,in order to improve the system efficiency and anti-jamming capability,a CAN interface circuit with high-speed differential transmission is designed.And based on the detecting principle of rotor position,a simplified resolving decoding circuit is designed.From the perspective of the drive capability,class B push-pull circuit is added in the drive circuit;by studying the issue of the parasitic turn-on of the IGBT caused by the Miller capacitance,an appropriate negative gate drive voltage is exploited.Considering the trade-off relationship between IGBT turn-off surge voltage spikes and switching losses,an appropriate gate drive resistance is selected.The reliability of the motor driver is improved adopting the above techniques.The detailed failure analysis of the motor driver is performed from the failure of the power main loop,the heat dissipation of the power module,and the electromagnetic interference.By studying the problem of surge over-voltage spikes during turn-off of IGBT,an absorbing circuit is added to the circuit for suppression and absorption,and failure protection circuits of over-voltage,overload,and short-circuit are designed to ensure that the high-voltage inverter circuits are able to turn off the IGBT timely under abnormal conditions.Based on the loss calculation of the power module,a reliable heat dissipation system and over-temperature failure protection circuit is designed to improve the stability of the system.By analyzing the electromagnetic interference environment of the motor drive system and taking restraint measures,the robustness of the system is improved.The main drive circuit in the motor drive is established under the Saber simulation software environment.And correctness of the drive circuit of the motor drive designed in this project is verified.Then the experimental device of the prototype is constructed.Through the performance test of the key unit of the motor driver,it is verified that the IGBT has good switching characteristics and the correctness of the designed resolver decoding circuit.