Research On Control Strategy Of Electro-hydraulic Compound Brake Of Four-wheel Drive Electric Vehicle

Distributed-driven electric vehicles are a hot research topic today and an important development direction for electric vehicles.Regenerative braking can effectively increase the vehicle’s mileage.The addition of regenerative braking to electric vehicles is an inevitable choice,and the difference between the response of the motor and hydraulic pressure in the electro-hydraulic composite brake will cause the brake to fluctuate.This paper takes a wheelside drive electric vehicle as the research object,mainly studies the control of the electrohydraulic composite brake under braking conditions,and designs the coordinated control strategy of the electro-hydraulic composite brake.The main research contents are as follows:Firstly,Carsim,AMESim and Simulink are used to establish the electro-hydraulic composite brake simulation platform.The vehicle dynamics model was established in Carsim,the hydraulic brake circuit model,ABS circuit model,motor model and battery model were established in AMESim,and the electro-hydraulic composite braking strategy framework was established in Simulink,and simulation verification was carried out,To establish a foundation for later research.Secondly,the electro-hydraulic composite brake control strategy was established,including the conventional electro-hydraulic composite brake coordination control strategy and the motor and ABS composite brake coordination control strategy.Conventional electrohydraulic hybrid braking coordinated control strategy refers to a control strategy designed for inconsistent braking sensation and brake shock without electro-hydraulic response without ABS intervention.The strategy includes a brake sensation consistency compensation algorithm,a switching mode judgment module,an impact limitation module,and a fuzzy PID control algorithm,and offline simulations are carried out under four different brake switching conditions.The comparison of the simulation results proves that this Strategies can improve braking comfort.The compound brake coordination control strategy of motor and ABS refers to the control strategy designed for the contradiction of braking between motor and ABS when ABS intervenes.The contradiction between the motor and ABS is analyzed,and the coordinated control strategy of the motor and ABS based on the electro-hydraulic response characteristics is designed.The offline simulation is carried out under three different road surface coefficients and braking strength.The simulation results prove the strategy It can solve the problem of contradiction in braking when the motor and ABS work together.Finally,a hardware-in-the-loop experimental platform was established.The d SPACE platform was used to verify the real-time control strategy.The conventional electro-hydraulic composite brake coordination control strategy and the motor and ABS composite brake coordination control strategy were simulated in real time.The ring simulation results show that the two strategies can solve the problems in the electro-hydraulic composite braking in real-time environment,which proves the real-time and effectiveness of the strategy.