Modelling And Control Of Vehicle Braking System Equipped With Electro-Mechanical Booster

With the rapid development of the internet and the continuous development of new energy sources,under the guidance of national policy,the new energy vehicle and intelligent vehicle developed vigorously,that bring more challenges and higher requirements for the automobile brake system.Specifically,the new energy technology claims that electric power replaces the traditional energy that will influence the use of the vacuum booster,so the new brake system needs to be developed.While the intelligent requires that vehicles reduce dependence on drivers and improving the accuracy of the control system.In addition,The vehicle braking system should take full consideration of the personal characteristics of the driver.The vehicle braking system equipped with electro-mechanical booster is mainly powered by the motor.The system can realize active pressure control and can fit the intelligent technology of vehicle perfectly as the bottom actuator,at the same time,the system can better realize the coordination with the regenerative braking,what's more,the adjustable power characteristics meet the different requirements of drivers.Finally,the system also has the function of failure backup to ensure the safe driving.Relying on the natural foundation project and horizontal item,the paper conducts the research on power control and active pressure control.In order to make it more convenient to design the control strategy,first,the related components of the system are tested,then,the whole system model is built,finally,considering the nonlinear factors of the system,the system power control algorithm and the active pressure control algorithm are designed.The main contents of this paper include:(1)Design and characteristic test of the vehicle braking system equipped with electro-mechanical booster.From the aspect of function definition and project design,the vehicle braking system equipped with electro-mechanical booster is described in detail,and the specific working principle of the vehicle braking system equipped with electro-mechanical booster is introduced.Then the test bench of electro-hydraulic braking system is built,it mainly includes hydraulic brake system,dSPACE software platform and the related sensors.Finally,the feedback disk was tested and the PV characteristic for the hydraulic brake system was tested.(2)Modelling of the vehicle braking system equipped with electro-mechanical booster.The system dynamic model is built based on the dynamic relationship,include the PMSM model,the electro-mechanical booster model(include the transmission model,the feedback disc model,the input push rod model and the output push rod model),the system friction model and the hydraulic brake system model.Finally,the system model was validated based on the experiment data.(3)Research on the base power control of the vehicle braking system equipped with electro-mechanical booster.First,the power characteristic curve of the vacuum booster is analyzed,and the realization method of its power control is studied.Then,based on sliding mode control technology and PID control technology,the control strategy of PMSM is built,including displacement loop,speed loop and current loop.Finally,the effectiveness of the control strategy is validated by the simulation and the hardware in the loop experiment.(4)Research on the active pressure control of the vehicle braking system equipped with electro-mechanical booster.Firstly,based on the characteristics of the active pressure,the electro-hydraulic brake system is simplified and analyzed.Then the active pressure control strategy is designed,including the triple step control algorithm,the flux weakening control algorithm and the pressure loop control algorithm.Finally,the effectiveness of the active pressure control strategy is validated by the simulation and the hardware in the loop experiment.