Power Battery Pack Multi-objective Optimization Design

Power battery pack is one of the most important system components of electric vehicles,which will work properly will affect the performance of electric vehicles.On the one hand,for the power battery pack,temperature control is one of the core works of the system,so heat management of the power battery system is an indispensable work in electric vehicles research and development.On the other hand,the battery pack at the bottom of the car often faces some extreme conditions,and the power battery pack vibration generates certain deformation,the deformation amount will threaten the battery and even the vehicle,so the vibration deformation of the power battery pack Control is also critical.But now some scholars have integrated the heat sink and vibration conditions of the power battery pack,and the optimization of the project is usually consumed.This thesis optimizes the power battery pack from the following side,the main contents:（1）This thesis proposes and constructs an NCM lithium battery module,and the simulation and analysis of thermal characteristics in different environments,respectively,with the NCM lithium battery module at normal temperature,high temperature 3600 s after discharge The temperature distribution was analyzed,found that the highest temperature was 49.4 °C in normal temperature,and the highest temperature was 59.0 °C under high temperature.In addition,the NCM lithium battery module under low temperature conditions is analyzed,and the minimum temperature of the module reaches8.56 °C.According to its normal temperature,high temperature and low temperature,several different heat dissipation and heat-cooling boards are designed according to the heat dissipation and voltage drop characteristics,from several types of liquid cold plates to select a double into the cold plate.Final cold plate.（2）The battery pack consisting of the battery module is fixed to the bottom of the car,which is subject to the overall vibration incentives from the outside,and threatens the safety of the battery and even the vehicle.So for power battery packs and modules,not only need to pay attention to their thermal characteristics,but also pay attention to their vibration characteristics.Therefore,this thesis selects extreme working conditions of the vibration to analyze,the dynamic performance of the power battery pack of the three extreme working conditions of turning,bumps and brakes are analyzed.The maximum amount of deformation is caused by vibration under the bump condition,so this deformation amount is reduced as a target,and multi-objective optimization is performed in subsequent chapters.（3）Based on the heat dissipation conditions and vibration conditions of the battery pack,this thesis has made multi-objective optimization design for the NCM lithium battery packs.This thesis has selected double imported dual exit snake channel based on temperatuere and pressure drop performance,then selected the maximum variation of the battery module,the maximum temperature of the battery module,the maximum amount of the battery module under bumps as design target functions.The NSGA-Ⅱ algorithm with better optimization effect is used for multi-objective optimization of lithium battery modules,and the optimization results show that the design can comprehensively balance the temperature and vibration of lithium battery modules.Whether it is the maximum temperature,pressure drop between inlet and outlet,or the maximum deformation,optimized design has achieved great improvement relative to the initial design,improves the safety and reliability of lithium battery modules.