Research On Electromechanical Composite Braking Force Distribution Strategy Of Electric Vehicle And Multi-Condition Simulation

In recent years,the growing number of vehicles has made environmental and energy security problems increasingly serious,and the development of electric vehicles provides a solution to this problem.However,there are many technical difficulties that limit the development of electric vehicles.One of these technical difficulties is the power battery technology,and it has led to relatively tight energy in electric vehicles.So,it is particularly important to improve the energy utilization efficiency of electric vehicles.Regenerative braking has become an important research and application direction as an effective technical approach to improve the energy utilization efficiency of electric vehicle power batteries.Regenerative braking technology converts part of the kinetic energy of the car into electrical energy by operating the motor in generator mode during braking,and the electrical energy finally return to the power battery to reduce energy loss.Due to the braking force of electric motor is limited and being susceptible to many factors.Under some braking conditions,the motor and the mechanical friction braking force are required to work together in order to meet the braking force requirements under this condition.Therefore,the braking force of electric vehicles is electromechanical composite braking force,and the distribution method of the composite braking force is related to the performance of the electric vehicle braking system.In order to improve the performance of regenerative braking system of electric vehicles,this paper studies the electromechanical composite braking force distribution strategy,and designs a mechanical frictionelectric motor composite braking force distribution strategy which considers both energy recovery efficiency and braking safety.The main research contents are as follows:Starting from the design requirements of braking force distribution strategy of electric vehicles,the whole distribution strategy is constructed in three parts:Firstly,according to the braking force demand,the method of constructing a safe braking area is used to initially distribute the braking force between the front and rear axles;Then,according to the operating state,component performance and other limiting factors,the regenerative braking intervention state and degree are determined;Finally,the braking force on the drive shaft is redistributed.After the distribution strategy was designed,MATLAB/Simulink and CRUISE were used to establish the distribution strategy model and the vehicle model of the target vehicle respectively,and the co-simulation was carried out by using DLL method under the NEDC driving cycle and the self-constructed Taiyuan comprehensive driving cycle.The simulation results show that the designed distribution strategy has better application effect in both general and localized conditions,and has more obvious advantages in localized conditions.In this paper,the braking force distribution strategy is adjusted for some nonstraight or plain road conditions(long downhill conditions and turning conditions),and the feasibility and effectiveness of the designed long downhill distribution strategy are proved by co-simulation.Finally,the energy recovery test bench was introduced in detail,and combined with the current laboratory test conditions,the brake energy recovery bench test plan was designed.And the test errors that possibly occurred were also analyzed.