Air Cooling Strategy Of Power Battery Based On Minimum Energy Consumption

In recent years,due to the increasingly serious energy crisis and environmental pollution problems,the development of new energy vehicles has become the only way for the sustainable development of the automotive industry.At present,most of the power batteries of new energy vehicles are lithium batteries,and the performance of lithium batteries is extremely vulnerable to the influence of battery temperature.Once the temperature is too high,the capacity and cycle life of the battery will decrease,and even lead to automobile combustion and explosion.In addition,in order to meet the demand of automobile power,power batteries in the process of operation constantly generate charging and discharging reactions,thus accumulating a large amount of heat.If these heat cannot be expelled in time,it will aggravate the accumulative temperature of battery pack.Therefore,it is necessary to timely and effective heat dissipation of power battery packs during operation.Among many methods of heat dissipation for battery packs,air cooling is a common method of heat dissipation for battery packs in electric vehicles because of its simple structure and low cost.At present,the air cooling control strategies of power batteries are mainly divided into two types:fan full-range open type and temperature switch type,which have the shortcomings of large energy consumption and lagging heat dissipation respectively.Therefore,this paper presents an air cooling control strategy for power battery based on minimum energy consumption,which can effectively realize the timely,effective and energy-saving heat dissipation of power battery.The main research contents are as follows:(1)The temperature rise model of power battery based on vehicle navigation system is established.the mechanism of using vehicle navigation system to obtain the information of average speed and gradient of future road sections is expounded;the power demand model of the power battery in the future is established.the temperature rise model of the power battery is established based on the heat generation and heat transfer mechanism of the power battery.(2)The accuracy of temperature rise model of power battery is tested.A scheme for accuracy test of power battery temperature rise model is put forward:the actual charging and discharging situation of power battery pack is simulated and the temperature rise is checked by using the current information input to the battery test system;a test bench for testing the accuracy of the hardware-in-the-loop of power battery packs is built;a vehicle model is built by using the electric vehicle simulation software ADVISOR2002,and the working conditions of ARB02,HWFET and UUDSHDV with slope information are established;the maximum difference between the predicted temperature and the actual temperature is 0.3℃ and the maximum deviation is 0.7%.The results show that the temperature rise model of power battery based on vehicle navigation system has high accuracy and is a feasible temperature prediction scheme.(3)An air-cooling control strategy based on minimum energy consumption of forced fans is proposed.The control strategy and logic based on minimum energy consumption are introduced.;the concept of piecewise dynamic programming algorithm is put forward based on dynamic programming algorithm and road condition information of vehicle navigation system;the air cooling control model of piecewise dynamic programming is established;the temperature rise of power battery pack under windless condition is analyzed theoretically,and the 8th section which needs forced air cooling is selected to explain the process of calculating the optimum opening time and the optimum wind speed of the fan.the theoretical analysis shows that the maximum temperature of automotive power batteries is 39.97℃ and the temperature of batteries is always controlled within 40℃,which can meet the heat dissipation requirements of battery packs under the predicted operating conditions by using the air-cooling control strategy based on minimum energy consumption.(4)The simulation validates the heat dissipation effect and energy saving of the power battery air-cooling control strategy based on minimum energy consumption.The maximum temperature of power battery under the control strategy based on minimum energy consumption is 39.87℃ by using Fluent 15.0 software simulation,it can meet the requirement of heat dissipation under real-time working conditions;the multi-objective genetic algorithm is used to solve the minimum wind speed under the same test conditions with the maximum temperature 39.87℃ and the maximum temperature difference 5℃ of power battery pack under the same test conditions;comparing the heat dissipation and energy saving effects of three control strategies under the minimum wind speed,the results show that the air-cooling control strategy based on minimum energy consumption can control the temperature of the battery within 40℃,and the temperature difference between the cells is the smallest;the energy consumption is 89.96%of the total energy consumption of the fan,which is 52.79%of the wind energy consumption of the temperature switch control strategy.Therefore,the control strategy based on minimum energy consumption can meet the heat dissipation requirements of power battery pack and achieve the minimum energy consumption of fan.