Research On Low-voltage Power Management Strategy Of New Energy Vehicles Based On Intelligent Algorithm

With the continuous development of automotive technology,there are more and more types of electrical equipment in automobiles,users’ demand for vehicle electricity consumption is increasing,the proportion of electric energy consumption in vehicle energy is rising,and automotive power supply is developing towards complexity and diversification.The traditional low-voltage power management system usually uses lead-acid batteries,but with the continuous increase of on-board electrical equipment,the demand for electricity continues to increase,and lead-acid batteries have problems such as low energy density,short cycle life,and high maintenance and replacement costs,which can no longer meet the actual needs of users.In order to solve the after-sales problem caused by lead-acid batteries,combined with the working characteristics of lithium batteries,low-voltage lithium batteries instead of lead-acid batteries as low-voltage power sources for automobiles have become a research hotspot.Taking a pure electric vehicle model of a certain automobile company as the research object,in order to meet the growing demand for electricity users,reduce the energy consumption of the whole vehicle,and improve the charging efficiency of the battery,this thesis designs a 12 V lithium battery low-voltage power management system,builds a vehicle model of pure electric vehicle and the corresponding control strategy,and conducts simulation verification.The main research contents of the thesis are as follows:(1)The structure of the 12 V low-voltage power supply system was analyzed,the vehicle dynamics model was built,and the key components were modeled and parameter matched.The quiescent current management strategy,the low-voltage power supply energy management strategy and the low-voltage lithium battery charge and discharge management strategy are designed,which lays a foundation for the subsequent improvement of the battery charging strategy and the optimization of the energy management strategy.(2)In order to shorten the charging time of low-voltage lithium batteries,improve the charging efficiency of low-voltage lithium batteries,and extend the service life of lowvoltage lithium batteries,a four-stage constant current charging strategy based on SOC is proposed,and the charging strategy of low-voltage lithium batteries is improved,and the battery charging strategy model is established in MATLAB-Simulink for verification and analysis.The results show that the four-stage constant current charging strategy based on SOC has higher charging efficiency and shorter charging time than the constant current and constant voltage charging strategy based on SOC.(3)In order to optimize the utilization rate of vehicle energy,maximize the saving of electric energy,and extend the cruising range of the vehicle,two energy management optimization strategies are proposed.The first is to use a genetic algorithm to optimize the energy management strategy of low-voltage power supply with the goal of minimizing the power consumption of the whole vehicle per 100 kilometers.The second is to use particle swarm algorithm to optimize the energy management strategy of low-voltage power supply with the goal of minimizing the power consumption of the whole vehicle per 100 kilometers.Finally,MATLAB-Simulink and AVL-Cruise are used for joint simulation,and the two proposed energy management optimization strategies are simulated and compared under four working conditions: NDEC,CLTC,WLTC and 60km/h constant speed cruise.The simulation results show that the optimized low-voltage power supply energy management strategy can reasonably allocate electric energy,and the power consumption of the whole vehicle is reduced under different working conditions,which meets the requirements of vehicle economy.The low-voltage power energy management strategy optimized by particle swarm optimization is better than that optimized by genetic algorithm.