Research On Coordinated Control Strategy Of Electro-hydraulic Composite Braking With Integrated Braking Intention

The Electro-hydraulic composite braking is composed of regenerative braking and hydraulic braking,which is the key technology to improve the driving mileage of electric vehicles and optimize the safety braking performance.How to coordinate the regenerative braking and hydraulic braking with meeting the needs of the driver braking intention,ensuring both braking safety and energy recovery maximization,is the key problem in the field of Electro-hydraulic composite braking control.Therefore,this thesis takes the distributed electric vehicle as research object,and focuses on the coordinated control strategy of composite braking with integrated braking intention.Firstly,a real-time identification method for braking intention is proposed and verified.Based on the time dimension,the brake braking intention is analyzed as two layers,the behavior and status.Based on the HHM theory,a five-steps braking intention identification scheme is designed,which contains the signal acquisition,characteristic extraction,clustering precision,off-line learning and on-line identification.The off-line simulation results show that the accuracy rate of the seven braking behaviors self-learning training library and the five braking status self-learning training is over 95%.The real-time performance of the identification algorithm is verified by the Rapid Control Prototype tests.Secondly,a coordinated control strategy of composite braking towards energy recovery is proposed and verified.According to the regenerative braking characterstic,the limiting factors and the feasible region of the maximum regenerative braking torque are arranged.Based on the optimization theory,the coordination control strategy problem is converted into the global search for optimal solution.The objective function with considering the regenerative braking performance and braking stability is construct.Based on genetic algorithm,the optimal solution distribution under different braking conditions is searched.The rapid control prototype test shows that the optimal allocation strategy can better balance regenerative braking performance and braking stability,compared to the contrast I curve allocation strategy.Finally,a compound anti-locked braking control strategy is proposed and verified.Making full use of the structural characteristics of distributed electric vehicle that regenerative braking and hydraulic braking are independently adjustable,a stratified control strategy is designed,which contains ISMC-baesd sliding control and mode switching-based torque distribution control.The simulation tests show that the compound anti-locked braking control strategy can improve the sliding control precision,and realize the control imagination that hydraulic braking maintains relatively stable value and regenerative braking compensates the residual value fastly.The proposed coordinated strategy of composite braking with integrated braking intention,has practical application value for improving regenerative braking performance and vehicle stability of distributed electric vehicle,and also is a beneficial attempt for the application of advanced control algorithm in the anti-lock braking system.