| Energy depletion and environmental pollution have promoted the rapid development of new energy vehicle technology,the lithium-ion battery,with a single high voltage,small size,high energy density,wide range of working temperature and long life cycle,has become the first choice of clean energy alternative to fossil fuels.However,the thermal safety of lithium-ion battery has been one of the major obstacles to the development of electric vehicles,in the process of electric vehicle driving,the temperature of the lithium-ion battery must be in a safe range(-20 ℃ ~50℃),and the temperature difference of the lithium-ion battery does not exceed a certain value(5℃).In this paper,the resistance of the battery and the open circuit voltage of the battery are tested by the experimental equipment,the thermal physical parameters of the battery are calculated by theoretical formula.The thermal simulation model of the battery at different discharge rates is established and verified by experiments.The results show that the lithium-ion battery has great balance performance at small current discharge,the maximum temperature appears in the vicinity of the positive region,the minimum temperature appears in the air.With the increase of the discharge rate,the temperature difference of the core becomes larger.The battery discharge rate,the cooling fluid flow,the cooling channel geometry structure,channel layout of import and export be changed to study the thermal analysis of lithium-ion batteries cooling module.The results show that the increase of the cooling liquid flow rate can effectively reduce the difference between the maximum temperature and the temperature difference of the lithium-ion batteries.However,when the cooling liquid flow rate increases to a certain extent,this effect began to weaken.The maximum temperature and the temperature difference of lithium-ion batteries can effectively reduce by increase the number of flow channels.However,this kind of influence also decreased by the increase of the number of channels.The maximum temperature of the lithium-ion battery pack can reduce by increasing the aspect ratio of the square channel.When the battery discharged by 1C and 2C rates,the maximum temperature of lithium-ion is reduced by 0.58 K and 2.1K,respectively,when the ratio of the length and width is 5:1.Better heat dissipation effect can achieve by use alternative import and export channel.The analysis is extended to the lithium-ion battery pack.The cold plate used in the battery pack has five rectangular channels with a length width ratio of 3:1.The lithium-ion battery pack thermal analysis results show that the maximum temperature of the lithium-ion battery pack is 317.87 K,and the temperature difference is 2.57 K,meet the requirements of lithium-ion batteries.The maximum temperature of lithium-ion battery pack was analyzed by changing the cooling liquid flow rate and cooling liquid temperature.Finally,the BP artificial neural network is designed to predict the maximum temperature of the lithium-ion battery pack,which is based on the interaction of the cooling liquid flow rate,the cooling liquid temperature and the discharge rate. |
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