Research On Integrated Control System Of Regenerative Braking And Anti-Lock Braking For Electric Car

In order to cooperate with the "Energy-saving and New Energy Automobile Industry Development Plan(2012-2020)" issued by the state,accelerate the technological progress and industrial transformation of new energy vehicles,ease the pressure on energy and the environment,and meet the energy conservation requirements of the "Eleventh Five-Year Plan" For the long-term strategic goal of reducing emissions,this article carries out related research on the integrated control system of electric car regenerative braking(RBS)and anti-lock braking(ABS).When traditional fuel vehicles are braking,their kinetic energy is dissipated through friction and heat.When electric vehicles are braking,the motor can be used for regenerative braking.The kinetic energy during braking is converted into electrical energy and stored in the power battery,which can effectively save energy and Improve vehicle mileage.However,the power torque of the electric mechanism of electric vehicles is affected by many factors and changes all the time.It is difficult to meet the driver’s braking demand at any time,especially after the wheels are locked.Therefore,in order to maximize energy recovery and ensure vehicle braking safety Therefore,it is necessary to conduct integrated control of the two systems of RBS and ABS,which poses new challenges to the traditional braking system and its control theory.When the RBS/ABS integrated control system works,it is necessary to satisfy three evaluation indexes,including energy-saving indexes,braking feeling indexes and safety indexes,which are closely related and contradictory.Therefore,in order to balance the relationship between the three,it is necessary to solve the problems of hardware and software architecture design,brake force distribution,pressure control and so on.At present,major domestic and foreign universities,scientific research institutions,and major automobile companies have carried out relevant research on the above issues and have obtained certain research results.Most domestic companies are in the stage of theoretical analysis and simulation verification,and there is still a long way to go for the mass production application of key technologies.Foreign research started earlier and is more in-depth,with relatively mature product commercial applications in hardware and software,and there is good control effects.In order to satisfy the development requirements of the RBS/ABS integrated control system projects,the research results of braking energy recovery systems at home and abroad are investigated,and the key technology of the integrated control system is developed for a FAW-Besturn brand target electric car.The main research work is as follows:(1)In order to meet the performance requirements of the RBS/ABS integrated control system,the hardware and software solutions of the system are designed separately;And three evaluation indexes of energy saving,braking feeling and braking safety were proposed;And from the perspective of hydraulic control status requirements,the software and hardware schemes are analyzed to prove the feasibility of them.(2)Conduct mechanism analysis and experimental research on the key components of the RBS/ABS integrated control system,including the analysis of the control principle and response test of the key executive components of the regenerative braking system and the analysis of the structural performance and working characteristics of the key executive components of the hydraulic braking system..(3)Using modular hierarchical thinking,the RBS/ABS integrated control system control software is divided into hierarchical modules,and the control algorithms involved in each layer of modules are discussed separately,including the identification of braking intention and braking force distribution integrated in the brake controller Coordinated control algorithms with anti-lock braking.(4)For the underlying pressure control problem of the RBS/ABS integrated control system,propose three typical hydraulic control methods of step pressure control,linear pressure control and active pressurization control,and conduct in-depth research on their control principles,method characteristics and application status.At last,to improve system control accuracy and fault tolerance,we put forward ABS and RBS wheel cylinder pressure estimation method for engineering practice.(5)Build Simulink-CRUISE offline simulation model,compare and analyze the energy-saving effect of the system under different typical cycle conditions,and build a semi-physical simulation test bench to verify the control effect of the proposed control method,and finally carry out the actual road test verification.After researching and analyzing the above content,the following conclusions are obtained:(1)Utilize the existing resources of the research group to improve the traditional hydraulic brake system and increase the pedal simulation device,which can realize the single-axis decoupling of the brake master cylinder and the front axle wheel cylinder,while maintaining the consistency of the brake feeling and making the motor’s braking ability be maximized.(2)Based on the driver’s traditional braking habits,the braking force distribution algorithm is proposed that takes the target front axle demand braking force as the control target and the braking intensity as the real-time correction target,so that the braking force distribution is more reasonable and the control effect is optimized.Propose the RBS and ABS cooperative control algorithm,establish the RBS system exit algorithm,and solve the system control conflict.(3)According to three typical hydraulic control methods,control the solenoid valve and other hydraulic actuators,and calibrate their key parameters.At the same time,the actual application of different brake pressure states is carried out for engineering,and its control effect is better and its accuracy is higher.What’s more,propose a method for estimating wheel cylinder pressure,which significantly improves the algorithm’s fault tolerance.(4)The control algorithm studied is verified through offline simulation,bench and actual vehicle test.The test results show that the RBS/ABS integrated control system has good control effect,reliable and accurate identification of braking demand,and pretty energy saving effect.When emergency braking occurs,the wheel cylinder pressure can still better follow the demand hydraulic pressure and ensure pretty braking safety.