Research On Design And Control Of Direct Motor-Driving Brake-by-Wire System For Passenger Car

Nowadays,it is becoming the trend even the reality that automotive will be more clectric,intelligent,networked and lightweight,which puts higher requirements on the automotive brake system.The electric trend requires automobiles to abondon the traditional internal combustion engine drive mode and go for the motor drive mode,which forces the brake system to discard the traditional booster and cooperate with the drive motor to achieve regenerative braking action.The intelligent and networked trend requires automobiles to develop more driving assistance technologies,such as Autonomous Emergency Braking(AEB)and Adaptive Cruise Control(ACC),which requires the brake system to implement active control.The lightweight trend requires the brake system to be lighter and more intergerated.Therefore,it is very important to develop a kind of Brake-by-Wire system with higher intergration,faster response and higher controllability.As a new type of brake system,the Direct Motor-Driving Brake-by Wire system provides and regulates the brake pressure through motor and transmission mechanism to meet the requirements of “quick pressure building and precise pressure regulation” of the brake system.This thesis takes a passenger car as the target model,according to the topic of “Research on Desigh and Control of Direct Motor-Driving Brake-by-Wire System for Passenger Car”,there is the main research contents:(1)Structure scheme design of the direct motor-driving Brake-by-Wire system for passenger car.Firstly,this thesis carried out typical scheme comparation of the direct motor-driving Brake-by-Wire system,analysed and compared the characteristics and performances of the typical scheme.Secondly,this thesis carried out structure scheme design of the direct motor-driving Brake-by-Wire system according to the function definition,then described the configuration and working principle of the designed structure scheme.(2)Simulation platform construction of the direct motor-driving Brake-by-Wire system for passenger car.Based on the study of the overall structure of the direct motor-driving Brake-by-Wire system simulation platform,this thesis established the math model of the direct motor-driving Brake-by-Wire system including the direct motor-driving pressure suplly unit,the high-pressure accumulator pressure suplly unit,the solenoid valve,the wheel cylinder and the brake pedal,then established the simulation model based on Matlab/Simulink,which laid the foundation for the system control strategy design,simulation and expriment.(3)Research on control strategy of the direct motor-driving Brake-by-Wire system.Firstly.this thesis designed a “Pressure-Velocity-Current”three closed-loop control strategy for the Brushless DC motor(BLDCM),and optimized the pressure loop control parameters by Taguchi optimization design method.Secondly,this thesis designed a Fuzzy PID control strategy for the pressure regulating valve based on parameter optimization.Besides,this thesis designed a ABS layered control strategy for the direct motor-driving Brake-by-Wire system,the upper layer was a coordinated control strategy of the logical threshold and the sliding mode control,the middle layer was the time-sharing scheduling strategy for pressure regulation task and the bottom layer was the actuator control stategy,which including the BLDCM and the valve control strategy.(4)Research on simulation and expriment of the direct motor-driving Brake-by-Wire system.According to the ABS layered control strategy and the actuator control strategy,this thesis carried out the software simulation for the direct motor-driving Brake-by-Wire system to verify the pressure regulation performance and the ABS control performance.Besides,based on the Hardware-in-the-Loop test bench,this thesis carried out the expriment on the pressure regulation performance of the actuator.The simulation and experiment results proved: the structure scheme and the control strategy of the direct motor-driving Brake-by-Wire system designed in this thesis can meet the requirements of “quick pressure building and precise pressure regulation” of brake system and effectively prevent the wheel from locking.