Research On Power System Matching And Braking Energy Recovery Control Strategy Of Multi-hub Motor Electric Vehicle

For the defects of short driving range and low energy utilization efficiency of electric vehicles,the problem of low energy utilization can be solved by braking energy recovery method.Compared with the general centralized drive electric vehicle,the multi-hub motor electric vehicle has a special power system,the four wheels of the braking torque can be independently controlled,and the braking energy recovery efficiency is higher.But the difference of power system matching method and braking energy recovery control strategy has great influence on braking stability and energy recovery effect.Therefore,the powertrain matching method and braking energy recovery control strategy are studied in this paper for multi-hub motor electric vehicle.Firstly,the vehicle parameters and dynamic performance indicators are determined.According to the vehicle’s power demand and the distribution characteristics of vehicle load in braking conditions,the parameter matching calculation method of multi-hub motor electric vehicle powertrain was studied.The power,torque and speed of the four motors in front and rear axles,as well as the rated energy,capacity and quantity of the battery were calculated by this method,and the motor and battery were selected.Then,the AVL＿CRUISE software is used to build a multi-hub motor electric vehicle model.The physical interface and communication interface of each module in the vehicle model are connected correctly,and the parameters calculated above are input into each module.Then,the calculation tasks of power performance and economy are added and set,and the simulation is carried out.Finally,the vehicle acceleration performance,maximum speed,hill climbing performance and NEDC driving mileage all meet or even exceed the set indicators,which proves that the parameter matching method in this paper is feasible.Then,in accordance with ECE regulations,in order to maximize energy recovery as the goal,an energy recovery control strategy based on parallel braking was designed.This strategy can be based on different braking mode,flexible control of the vehicle front and rear brake force and motor regenerative and mechanical braking force distribution ratio.On the basis of full consideration of braking safety,priority is given to motor braking,mechanical braking to supplement the remaining braking force.At last,the braking energy recovery control strategy designed in this paper is modeled by MATLAB /Simulink software,and the co-simulation is carried out with the vehicle model built in AVL＿CRUISE.Firstly,under different initial braking conditions,the results show that the motor and mechanical torque changes and braking distance of the front and rear axles in the braking process have achieved good control effect,and the energy recovery efficiency is high.In the NEDC cycle,the results show that the motor and mechanical torque change,speed following and energy recovery of the front and rear shafts have achieved good control effect during the simulation.Compared with the condition when the control strategy is off,the energy consumption level of the battery is significantly reduced in the on state.The results show that the control strategy designed in this paper can not only ensure the stable braking of the vehicle,but also ensure the good effect of energy recovery,and achieve the expected goal of this paper.