Research On Control Strategy Of Thermal Management System Of A Certain Pure Electric Passenger Car In Low Temperature

As one of the important pillar industries in my country,the automobile industry,the current challenges mainly come from the increasing shortage of oil resources and the increasing pollution of the ecological environment,therefore,the focus of my country’s automobile industry has begun to shift to energy-saving and environmentallyfriendly new energy vehicles.However,the common problem of new energy vehicles,especially pure electric vehicles,is poor environmental adaptability,under high and low temperature conditions,especially in low temperature conditions,the driving range is seriously attenuated compared to normal temperature conditions.In the cold northern regions,the temperature is low in winter and the temperature difference between winter and summer is large.the capacity and charge-discharge performance of the power battery decays greatly in cold climates,the thermal management of the passenger compartment,battery and motor is isolated and scattered,there is no integrated and efficient thermal management system.Therefore,it is necessary to study the reasonable configuration of the thermal management system of pure electric vehicles under low temperature conditions,the rational utilization of vehicle heat,and the research on the control strategy of the thermal management system.This article is based on the school-enterprise cooperation project of the research group,research on the control strategy of the whole vehicle thermal management system of a certain pure electric passenger car,it is designed to ensure the performance of the battery at low temperatures,the driving range of the vehicle under low temperature conditions,and the reasonable utilization of the heat of the vehicle.This article first analyzes the development status of domestic and foreign power battery thermal management technology,passenger compartment thermal management technology and vehicle thermal management system architecture.Subsequently,the analysis of the thermal management system architecture of pure electric passenger vehicles was carried out.According to the different functions of each circuit,the thermal management system is divided into battery circuit,passenger compartment,motor circuit,refrigeration circuit and heating circuit.And on the basis of the thermal management system architecture of the target model,optimized the loop of the thermal management system,,and based on the optimized thermal management system loop,the different working modes of the thermal management system under low temperature driving conditions are divided.To study the performance and modeling needs of batteries at different temperatures,use the existing equipment of the research group to carry out related battery experiments,then use GT-SUITE software to make a onedimensional simulation model of battery,motor,passenger compartment,heating loop and vehicle power system.Based on the optimized thermal management system loop,the control strategy model of the thermal management system was built using Matlab/Simulink,and through the GT-SUITE software for co-simulation,after that,the joint simulation model of the thermal management system was verified through the existing actual vehicle experimental data.The results show that the model can accurately describe the temperature changes of the battery,motor and passenger compartment and the energy consumption of the entire vehicle.Under different ambient temperatures,the temperature changes of the battery,motor and passenger compartment and the energy consumption of the vehicle will be affected to varying degrees.This paper selects the ambient temperature of-15℃,-7℃ and 0℃ as the typical working conditions at low temperature.To study the influence of different thermal management system control strategies on battery capacity attenuation ratio and vehicle driving range,Complete the formulation of the control strategy of the thermal management system under low temperature driving conditions.Finally,in order to reduce the energy consumption of the PTC heating stage for the passenger compartment and the battery at the same time,according to the battery temperature,a stage control strategy is formulated,A multi-objective optimization model was constructed with the battery capacity attenuation ratio and PTC energy consumption as the optimization goals.After optimization by genetic algorithm,according to the different weight coefficients of the objective function,got multiple sets of simulation results,and through the Pareto boundary,the optimal solution for the best overall benefit is obtained.When the weight coefficient of the objective function is 0.25,at an ambient temperature of-15°C,within a CLTC driving condition,compared with the original control strategy,the stage control strategy at the expense of 1.4% battery capacity degradation ratio,which makes PTC saved 10.73% of energy consumption.Achieved the goal of saving energy during the PTC heating phase for the passenger compartment and the battery at the same time.