Study On Driving Energy Management And Control Strategy For Extended Range EV

As energy crisis and environmental pollution have become the biggest obstacle of traditional fuel vehicle development,the rise of electric vehicles has been overwhelming.But,the energy density,life,and cost of battery applied to electric cars still can't meet the consumers' demand.In order to deal with this problem,an auxiliary power unit(APU)is added to electric vehicles,then the extended-range electric vehicle is formed,which can provide the vehicle energy for driving when battery power is exhausted,is a very suitable transition for the present situation,has gradually been taken seriously by our country,the major car companies and consumers.However,the traditional driving control strategies of extended-range electric vehicle need more comprehensive consideration of battery efficiency and engine fuel economy,they don't make the most of vehicle energy.So,this paper will continue to study and improve the traditional driving control strategies of extended-range electric vehicle.In order to deal with the low integrated energy utilization efficiency of traditional extended-range electric vehicle control strategy,this paper compares the battery charge and discharge efficiency when the vehicle is only driven by the battery with the engine fuel economy when the vehicle is only driven by the engine,then presents a control strategy based on vehicle energy demand and current vehicle status to allocate energy flow to improve the vehicle economy.In addition,due to the improvement of battery charge and discharge efficiency,the battery can in a certain extent avoid the charge and discharge process which will lead to attenuation of battery capacity,improve the battery life.The specific research contents are as follows:1.Based on a collaborative project of developing a pure electric city bus,this paper treat the car's basic parameters and dynamic design objectives for the vehicle as the target,reduce the capacity of the battery pack in reference to the national subsidy policy,then add an auxiliary power unit,complete the matching and selection of main components.2.Description the control scheme and principle of the conventional Thermostat Control Strategy and Power Follower Control Strategy of extended-range electric vehicle,then points out the shortcomings of traditional control strategy,combining with the current research results on battery efficiency and engine fuel economy,this paper puts forward the minimum instantaneous equivalent consumption control strategy.This strategy compares the equivalent power consumption of pure electric driving with the engine only driving to determine the engine start or stop,and if the engine is turned on,then calculate the comprehensive energy consumption of the vehicle in each point of the engine efficient area,choosing the point of lowest comprehensive energy consumption as the engine operating point.3.According to the result of parameter matching,the vehicle simulation model is built with AVL Cruise,and building the Matlab/ Simulink control model on the basis of the control strategy,and then do co-simulation with the vehicle model and control model.Finally,the control effect of the three control strategies is compared and the conclusion is as follows: the minimum instantaneous equivalent consumption control strategy has the best economy,whose equivalent fuel consumption is 10.38% to 12.39% lower than Thermostat Control Strategy and 5.34% to 6.89% lower than Power Follower Control Strategy,and in pace with temperature decreases,the difference with Thermostat Control Strategy increases,the difference with Power Follower Control Strategy reduces.This paper is based on the study of the charge and discharge efficiency of battery and the fuel economy of engine,aiming at the lowest equivalent fuel consumption,puts forward the minimum instantaneous equivalent consumption control strategy,which provides a reference for the development of the control strategy of extended-range electric vehicle.