Research On Braking Coordination And Stability Control Strategy Of Hybrid Electric Vehicle

Hybrid electric vehicle are widely accepted by people because of its economic,mature technology and country's strong supporting.In order to improve the energy recovery efficiency of hybrid vehicles,people focus on the regenerative braking system.As the main implementing agencies of the vehicle stability control,drive anti-skid and other active safety system,electronic control hydraulic braking system,which has become a research hotspot in recent years.In the braking process,the traditional car just to ensure the safety of the brake,compared to the traditional car,the hybrid vehicles can recover energy as much as possible on its basis,and the braking requirements of the brake safety is shared by the regenerative brake and electronic control hydraulic brake,but the regenerative braking force will be influenced by the current state of the vehicle,motor,battery efficiency and other factors.Therefore,how to make regenerative braking and electronic control hydraulic braking system in coordination with each other to ensure the safety of hybrid cars and to improve the efficiency of energy recovery,which is necessary.In this paper,I make the following research under the support of national key scientific and technological research and development project(JFYS 2016 ZY 02001610-02):Firstly,The coordinated control system of the simulated automobile brake is designed,and the hydraulic part of the corresponding electronic control hydraulic braking system is modeled by Matlab/Simulink software;For the regenerative braking system,we make the battery,flywheel and permanent magnet synchronous motor AMESim model.Secondly,Using the above model,and use the fuzzy PI controller to control the duty cycle(PWM),to adjust the braking torque of the electronic control hydraulic braking system by change the switching frequency of the inlet and outlet solenoid valves.For the permanent magnet synchronous motor in regenerative braking system,using the method of space vector control to track and control the torque of the motor.To analyze the factors of regenerative braking,and to consider the charging characteristics,braking strength and vehicle speed of the battery,and on the basis of ensuring the stability and safety of the vehicle,To analyze the influence of electronically controlled hydraulic braking and regenerative braking by using the hybrid theory,in order to make the regenerative braking and electronically controlled hydraulic braking system can cooperate with each other.Thirdly,Using the two-degree-of-freedom vehicle model to calculate the nominal value of the control variable,and using the fuzzy control to determine the stability threshold of the vehicle;The stability of the vehicle is calculated by using the stability control strategy of the sliding mode variable structure.The stability threshold is used to decide whether the stability of the vehicle is stable.If the vehicle is unstable,the additional brake is realized by the coordinated braking system,to use the coordinated braking system to achieve the required additional yaw moment.And then,based on the joint simulation platform,the validity and robustness of stability control of sliding mode variable structure control that proposed in this paper are verified under various typical conditions.