Research On Thermal Management System Of Power Battery Based On FCV

Under the influence of the oil crisis and environmental protection,new energy vehicles are gradually replacing traditional fuel vehicles.Hydrogen fuel cell vehicles have developed rapidly with the advantage of zero pollution emissions.Power batteries are used as auxiliary power sources for hydrogen fuel cell vehicles,and their performance is affected by temperature.A large,excessively high ambient temperature will cause a large amount of heat inside the battery to be dissipated in time,causing a fire and explosion accident;working at an excessively low ambient temperature will drastically reduce the battery’s charge and discharge capacity and electrochemical performance,thereby greatly reducing the battery’s operating efficiency.A properly designed thermal management system can effectively solve the problem of excessively high or low battery temperature or excessive temperature difference,which is of great significance for the safe use of hydrogen fuel cell vehicles.The main contents of this paper are as follows:(1)Analyze the heat generation and heat transfer mechanism of the lithium battery during the working process and make a comparative analysis of the heat generation rate calculation under different electrochemical thermal coupling models.By comparing the advantages and disadvantages of different electro-thermal coupling models,the semi-empirical Electrochemical thermal coupling model.(2)Taking the lithium iron phosphate battery produced by a company as the research object,the auxiliary power source of a fuel cell heavy truck was subjected to power matching,and the current distribution of the power battery under different operating conditions was calculated,and the vehicle was obtained under the US06 operating condition.The larger the current output,the greater the heat generation rate.Therefore,the high-speed conditions are used as the research conditions to determine the heat generation rate corresponding to the 1C discharge rate as the heat source input for the subsequent thermal simulation.(3)The charge-discharge experiments of different power batteries were carried out to obtain the electrothermal characteristics of nickel-metal hydride,soft-pack lithium polymer batteries and lithium iron phosphate batteries,and the important parameters of the model were obtained through experiments.The thermal characteristics of the lithium iron phosphate battery pack were studied experimentally,and it was found that the temperature of the connecting line between the battery pack connecting tab and the battery’s total positive and negative electrodes was significantly higher than the battery body temperature.(4)An experimental platform for heat dissipation and preheating of the battery pack was built,and parallel air cooling and electric heating film heating experiments were performed on the power battery to prepare for the feasibility verification of the corresponding model later,and obtained:a)the average wind speed at the entrance of the parallel channel At 2.5m/s,the temperature in the middle of the battery pack is slightly higher than the edge of the battery pack,and the temperature of the battery pack edge near the entrance of the channel is slightly lower than the temperature near the outlet;b)The heating power of the heating film is 30W,and the heating time is The maximum temperature after 540s is 29.5℃,the maximum temperature difference is 3℃,and the maximum temperature rise rate is 1.6℃/min.According to this condition,it is minus 20℃.The temperature of the battery pack needs to be raised to 0℃ in 14 minutes,and the temperature difference is not more than 5℃.(5)Simulation and calculation of the temperature field distribution of the battery module under natural air cooling,serial air cooling,and parallel air cooling heat dissipation,and the temperature distribution of the battery module after preheating at low temperature,to obtain the natural convection on the battery pack The heat dissipation effect is not obvious,and it cannot be guaranteed to work in the optimal temperature range.Serial air cooling is not conducive to the power battery working under high temperature conditions.In parallel air cooling,the maximum temperature of the battery pack varies with the inlet wind speed.Increase and decrease,the temperature uniformity fluctuates as the inlet wind speed increases,and as the battery spacing increases,the maximum temperature of the battery pack gradually decreases,the temperature difference decreases first and then increases,the influence of the battery margin on the maximum temperature Smaller,the temperature difference decreases first and then increases.The bottom heating is more conducive to the uniform temperature of the battery module than the side heating.The side heating can better meet the time requirements of the cold start of the vehicle,but it is not conducive to temperature uniformity.In this paper,through the combination of experiment and simulation,the auxiliary power source of the hydrogen fuel cell vehicle is studied in parallel with air cooling and electric heating film heating,which provides a certain experimental and simulation basis for the thermal management design of the hydrogen fuel cell vehicle.