The Multi-objective Optimization Of The Electric Vehicle Contains Battery Pack Cooling With High Temperature Radiation And Low Wind Drag

Battery is the engine of electric vehicle,and the endurance mileage can't satisfy the psychological demand of long-distance driving,which restricted its development.It is an effective way to improve the battery endurance by reducing the aerodynamic resistance of the body,avoiding the high temperature of the battery and realizing the uniformity of the temperature between the cell module and the single battery.In addition,the main cost of the electric vehicle is the battery.It is important to realize the good heat dissipation of the battery to improve the thermal fatigue life.Thus,in order to maximize battery endurance,after determining the number of batteries on the basis of the power demand of the electric vehicle,the structure of the battery pack is studied in the three-dimensional curved surface under the constraint of the vehicle body.On this basis,in order to obtain a more accurate temperature distribution of the battery pack,the effects of solar and terrestrial thermal radiation on the heat dissipation are studied,and the optimum cooling structure of the battery pack under forced air-cooled mode is explored through structural improvement optimization.Then,in order to increase the battery endurance,taking the size and position of inlet and outlet as optimized objects,this paper carried out multi-objective optimization research on aerodynamic drag reduction and battery pack heat dissipation,which was based on the surface free deformation technology,selected the key surface factor,and carried out the search of body aerodynamic drag reduction.The specific research contents are as follows:1.The classical cylindrical monomer lithium battery for automobile is studied,this paper analyzed the heat producing mechanism of lithium-ion battery,established the monomer model,determined the heat-transfer and heat conduction model of lithium-ion,carried out numerical simulation,and compared the discharge experiments of single lithium ion with 1C magnification,and on the basis of verifying the accuracy of simulation calculation,the heating rate and temperature rise characteristics of the monomer are studied,and a wind tunnel test is carried out for the vehicle body model,which provides the calibration data base for the numerical simulation of body outflow field and aerodynamic drag reduction.2.Without changing the shape of the body,according to the power demand,the frequently-used battery pack structure is designed,and the optimal research of the automobile low aerodynamic drag is carried out under different arrangement modes.Considering the summer high temperature radiation,such as solar radiation and road surface radiation,the optimal battery layout and the thermal structure of the battery pack are explored without changing the body shape,which were based on the arrangement of the lowest wind resistance.3.Considering aerodynamic key influential factors as the optimization variable,the optimal Latin hypercube is used to generate the sample points of the optimization variable,and the deformation sampling of the body geometry model is carried out,taking the improved characteristic size of the battery package and the geometrical features of the vehicle body which influence the key factor of aerodynamic characteristic as the constraint.After obtaining the aerodynamic drag coefficients of each sample point,the approximate model of response surface is constructed,and the multi Island genetic algorithm is used to optimizing the global low resistance of vehicle body.4.The inlet grilling and outlet size and position of the front face of the body have important influence on the heat dissipation and aerodynamic drag of the battery pack.Based on the Isight optimization platform,this paper regards the size and position of inlet grilling and outlet as variables,and carries out multi-objective optimization research on the optimal heat dissipation structure of body aerodynamic drag and maximum temperature of battery pack to obtain the low wind resistance and excellent battery pack heat dissipation performance of the pure electric vehicle model.Compared to the original car body model,the aerodynamic drag coefficient reduce by 9.97%,the maximum temperature is about 315.66 K under high-temperature operating conditions,and the temperature difference between the single battery is around 5K,effectively maximizing the endurance,extending the battery life and ensuring battery safety.