Simulation And Experimental Study Of Electro-hydraulic Combined Braking System For Heavy-duty Vehicles

With the rapid development of the global automotive industry and the increase in car ownership,global energy and environmental issues are facing severe challenges.Electric vehicles have become the new development direction of the automobile industry and the inevitable choice for building an environment-friendly society,with its advantages of energy saving and environmental protection.However,due to battery technology,electric vehicles have a short driving range,and energy recovery technology is required to increase the driving range.The electric vehicle regenerative braking system can convert the drive motor to the power generation mode during braking,and achieve regenerative energy recovery while providing regenerative braking force for vehicle braking.Therefore,regenerative braking technology is the key technology for the innovative development of electric vehicles.However,the braking strength of the regenerative braking system is not enough to independently complete the vehicle braking task.It needs to cooperate with other forms of braking systems to jointly provide the braking force required for vehicle braking.The thesis takes electric heavy-duty vehicles as the application object,and proposes an electro-hydraulic combined braking system that can work in conjunction with a motor regenerative braking system.The combined braking system is composed of an electro-hydraulic braking system and a full hydraulic braking system.When the vehicle is braking normally,the required hydraulic braking force is provided by the electro-hydraulic braking system except the regenerative braking system.When the electronic control unit of the vehicle braking system fails,the full hydraulic braking system independently completes vehicle braking.The paper analyzes the working principle and characteristics of the electrohydraulic combined braking system and its components in some detail,and then establishes the Simulink and AMESim simulation models.Based on the simulation model,the classic PID and fuzzy adaptive tuning PID control algorithms of the hydraulic brake by wire are designed,and the two algorithms are simulated and analyzed separately.Finally,in order to further grasp the characteristics of the electrohydraulic combined braking system,the paper designs and implements a braking experiment.Through theoretical analysis and experimental research,it is verified that the electro-hydraulic combined braking system has high braking pressure adjustment accuracy,rapid braking response and high reliability,which meets the performance requirements of the heavy-duty vehicle braking system.The electro-hydraulic combined braking system of the heavy-duty vehicle proposed in the paper can be applied to traditional engine-driven heavy-duty vehicles to improve the brake pressure control accuracy and brake response speed of the electrohydraulic braking system,and it can also be applied to pure electric heavy-duty vehicles,working in conjunction with the regenerative braking system,it achieves energy recovery while improving braking performance and increases the drive range of electric vehicles.