Research On The Control Strategy Of Hybrid Brake System For Distributed Electrical Vehicles

In recent years,air pollution of China is serious,vehicle exhaust is one of the sources of pollution.Reducing vehicle exhaust emissions plays an important role in mitigating air pollution.Electric vehicles with its high energy efficiency,no noise,zero pollution and other advantages have gradually attached importance to the domestic auto manufacturers and scientific research institutions in recent years also increased the intensity of electric vehicles R&D efforts,and they strive to seize the initiative in the field of electric vehicles.Electric vehicles are divided into the central electric vehicles and distributed electric vehicles.The distributed electric vehicles with its compact structure,the power chain short,high efficiency and outstanding advantages,can be four-wheel drive/brake system dynamic optimization of its energy-saving control by the majority of car manufacturers and scientific research institution.The distributed electric vehicle adopts the regenerative braking system and the electronic hydraulic braking system,they constitute the electro-hydraulic hybrid regenerative braking system.The system has a full wire and distributed architecture.It ensures the braking performance and stability under the premise of a reasonable allocation of four-wheel braking torque and the single-wheel electric and liquid brake ratio,it's a large extent recovery of electric vehicle braking energy to extend the electric vehicle driving range.The main research content of the paper is to explore the hybrid braking control strategy of distributed electric vehicle with hybrid brake system,which is divided into the following aspects:(1)Research on control strategy of motor braking system and hydraulic braking system.The regenerative braking control strategy of the wheel motor braking system includes the half-bridge unilateral chopper feedback control strategy,the half-bridge bilateral chopping feedback braking control strategy and the full-bridge chopper feedback control strategy.The paper analyzes theoretical motor brake control strategy,and finally determines the appropriate motor brake control strategy;hydraulic braking system control strategy adopts pressure closed-loop control solenoid valve duty cycle to achieve real-time adjustment of pressure.(2)Building a hybrid braking system co-simulation platform.Based on the EHB principle structure,AMESsim software is used to build the electronic hydraulic braking system simulation model,and the pressure closed-loop control part of solenoid valve is built by SIMULINK software.The mechanical control system of the wheel motor is built by MATLAB/SIMULINK software.Then they make co-simulation to explore the appropriate hybrid braking system control strategy with CarSim software in vehicle model.(3)Research on control strategy of hybrid braking system.The vehicle controller distributes the total braking torque of the single wheel according to the coordination and distribution strategy of the front and rear wheel.The braking control unit allocates the single-wheel braking force and the hydraulic braking force to the control target by maximizing recover braking energy under the premise of ensuring the braking performance and the braking stability.According to the motor torque,the output characteristic is preferentially motor braking,and the compensation is hydraulic braking and the hybrid braking co-simulation model is used to verify the hybrid braking control strategy.(4)Bench verification of single-wheel hybrid braking system.The designs of the hybrid braking system platform include motor braking test bench program,the software and hardware of in-wheel motor controller,and the selection of the corresponding components.The test bench is used to verify the motor driving/braking control strategy.