Research On Response And Experiment Of Direct Motor-Driving Brake-by-Wire System For Passenger Car

With the development of new energy vehicles and intelligent networked vehicles,it has become an inevitable trend to develop brake-by-wire systems with high integration,good brake performance and stability.In addition to meeting the basic braking requirements,the brake-by-wire system can also help the vehicle to achieve intelligent assisted driving functions such as ABS,ESC,TCS,ACC,AEB,etc.Including regenerative braking function.It has the characteristics of “active and rapid pressure building and precise pressure control”.The response characteristics of the brake-by-wire system and the design of the controller are the key cores to achieve the above functions.Therefore,this paper relies on the “Key Technology Research and Product Development of Intelligent Assisted Driving of Electric Vehicles” of the National Key Research and Development Plan,focusing on the “Research on Response and Experiment of Direct Motor-Driving Brake-By-Wire System for Passenger Car”,researching from simulation model establishment,control strategy research,key parameters of brake system to make response characteristics analysis and simulation analysis under various braking conditions,hardware-in-the-loop test and other key issues:(1)According to the mathematical model of each component of the direct motordriving brake-by-wire system,the simulation model is built based on Matlab/Simulink simulation software.According to the input and output relationships of each component of the direct motor-driving brake-by-wire system,the simulation model of each component can be connected into the direct motor-driving brake-by-wire system.The simulation model of brake system can be used to study the influence,which key structural parameters of the system have on the response characteristics of the system.It is also a simulation platform for studying the response characteristics of the system under various braking conditions.(2)The control strategy of the direct motor-driving brake-by-wire system is studied,including the actuator controller and the ABS controller.In the actuator controller,a pressure-speed-current three-loop controller is designed for brushless DC motor.The pressure control loop adopts fuzzy PID control algorithm,the speed control loop adopts incremental PID control algorithm,the current control loop adopts current hysteresis control.And the pressure-regulating solenoid valve adopts real-coded genetic algorithm PID controller,using switch control for the pressure reducing valve.In addition,the ABS controller is also designed,which uses a sliding mode variable structure controller based on the double power approach law.(3)Analyzing the key structural parameters of the brushless DC motor and solenoid valves,simulating influence analysis on the response characteristics of the direct motor-driving brake-by-wire system,carrying out the experimental optimization design analysis of the key structural parameters of the system,and obtaining the optimal parameter scheme.According to the Matlab/Simulink simulation model of the direct motor-driving brake-by-wire system,which are combined with the designed brushless DC motor controller and pressure-regulating solenoid valve controller,making simulation analysis of response characteristics under common braking conditions such as conventional braking,autonomous emergency braking and so on.The simulation analysis of ABS braking condition was carried out by using the joint simulation platform composed of Matlab/Simulink and CarSim.The simulation results show that the designed actuator controller and ABS controller are effective.(4)A hardware-in-the-loop test bench for the direct motor-driving brake-by-wire system was built.Using the hardware-in-the-loop test bench to verify the following pressure response of step,slope,sine of the front right brake wheel cylinder,also verifying the response characteristics of the direct motor-driving brake-by-wire system and the effect of the actuator controller.The test results show that the direct motordriving brake-by-wire system has a fast response,high pressure control accuracy,and a good overall effect of following the target pressure.