Research On Electro-Hydraulic Braking System And Its Regenerative Braking Control Strategy

Electro-Hydraulic Braking System(EHB)as a result of the transition from the traditional brake system to the brake-by-wire system,has been favored by the major host plants and parts manufacturers.Based on the brake-by-wire system and wheel cylinder brake unit of traditional brake system which make the EHB become the most ideal configuration of new energy vehicles and unmanned vehicles.Also,EHB is a new trend in the field of braking technology development in the near future.Based on the school enterprise cooperation project,this thesis puts forward a new type of hydraulic braking system based on integrated master cylinder.The structure principle,function and control method of the braking system are studied in detail in this thesis.Based on AMEsim,Simulink,CarSim and test bench,this thesis discusses the system characteristics and control methods of EHB.The main contents of this thesis are as follows:(1)This part mainly introduces the development status of EHB,including the research results of the foreign major parts manufacturers,the main products of the host plant and the major universities and enterprises in China.Based on the advantages and disadvantages of the EHB products,the thesis introduces the three modes of the proposed EHB: normal mode,backup mode and ABS mode.(2)Modeling of the key parts of EHB is introduced.AMEsim is mainly responsible for hydraulic part while SIMULINK for control part.Braking performance is tested under three modes through the match of EHB model and vehicle model in CarSim.PWM control method is used to control the booster valve and pressure relief valve in order to better achieve the braking pressure following in EHB.In addition,in order to validate the feasibility of ABS function in EHB,the four phase double logic threshold control method is used.(3)Through co-simulation,the hydraulic characteristics of EHB are studied,and the effect of key parameters on the pressure increase and relief rate of brake system is analyzed.Through the whole vehicle dynamics simulation,the normal mode,the failsafe mode and the ABS mode are discussed.(4)According to the structural characteristics of the EHB system,the control strategy of the series braking energy recovery is set up to verify the feasibility and superiority of the braking energy recovery in the EHB system.(5)The EHB system prototype test bench is built to verify the open and closed loop hydraulic characteristics of EHB system.In this thesis,the advantages and feasibility of EHB in normal,failsafe and ABS brake are verified by simulation and experiment.At the same time,the advantages of EHB in the process of braking energy recovery are discussed.These works have theoretical and practical significance to the EHB system in the new energy vehicles and unmanned vehicles.