Research On Dual-energy Source Storage System For Pure Electric Commercial Vehicle

The rapid development of the automobile industry has made a significant contribution to China's economic construction,and also brought the problems of environmental pollution and energy crisis.New energy vehicles,which are using new power systems and drived by new energy,can reduce emissions and pollution.Pure electric vehicle(PEV),which has many advantages such as high efficiency and energy saving and environmental protection,is an important development direction of new energy vehicles.It is also an important way to solve the problems of environmental pollution and energy shortage.PEV mainly uses li-ion battery as the power source,but its power density is small and the charge/discharge efficiency with large current is low and the lifetime is short and the cost is very high,which has become the major block for the development of PEV.Ultracapacitor with advantages of high charge/discharge efficiency and long lifetime is a new energy storage device,but it can't discharge continuously because of its low energy density.Therefore,the study on dual-energy source storage system which is composed of li-ion battery and ultracapacitor is meaningful.In this paper,a pure electric commercial vehicle using the li-ion battery as power source is the object of this study.The charging/discharging current of this vehicle is too large and the battery heats seriously and the lifetime is short when it is driving in the mountain city.So,we change the single-battery source storage system to dual-energy source storage system on the basis of the pure electric commercial vehicle's original power system.Firstly,this thesis analyzes the characteristics of different energy storage devices of electric vehicle and then chooses li-ion battery and ultracapacitor to compose the dual-energy source storage system according to the characteristics and technical conditions.Then,the dual-energy source storage system is matching based on the basic parameters of pure electric commercial vehicle.Energy control strategy of dual-energy source storage system is the focus of this study,and a fuzzy logic control strategy is established according to the road conditions of mountainous cities.Finally,the modeling and simulation are carried out with CRUISE and MATLAB.The results show that using the dual-energy source storage system for pure electric commercial vehicle can achieve the designed goals of dynamic system and meet the energy requirement of speed and acceleration.It also can avoid the impact on li-ion battery when it charged/discharged with large current during a short time,and increased the working efficiency of li-ion battery and the recovery rate of braking energy and finally prolong the lifetime of li-ion battery and increased the running range of pure electric commercial vehicle.