Research On Thermal Management Strategy Of Power Battery Based On Typical City Driving Cycles Of Electric Vehicles

Due to energy shortage and environmental pollution,electric vehicles in the recent 20 years have obtained rapid and great development.Power battery which is the key to battery cars would have a great influence to the future of electric vehicles.And battery thermal management system is the most essential for power battery technology,directly related to the safety and the lifetime of power battery and the electric car.This paper is in a 18650 manganese acid lithium power battery for the object based on application background of urban electric vehicle,the thermal c haracteristics of the power battery under the condition of typical city is on research,and the general law of temperature rise of power battery is summarized.And in view of the temperature sensor's lag issues,combined with the battery internal temperature estimation algor ithm,the battery thermal management strategy is proposed based on the inside temperature estimated.The battery thermal management system with the strategy which combines the temperature characteristic of power battery and the character istics of the operation condition of the electric vehicle could be maximum keep power battery working in an ideal temperature range by real-time monitor ing and feedback battery voltage,current,temperature and electric vehicle driving condition to improve the safety and service life of power battery and electric vehicle.The main research work is as follows:(1)The heat generating mechanism of the lithium battery is expounded and the influence factors of power battery temperature rise are analyzed.The relationship between heat production of battery and working condition of electric vehicle is clarif ied by the simulation based on software advisor under typical urban condition,and the output performance of power battery is gained to provide battery modeling and simulation with the data.(2)The method and classification of battery modeling are analyzed and a three-dimens ional electrochemical-thermal model is established based on Comsol Multiphysics software.Under typical urban conditions and different ambient temperature,some simulations about the battery module and cell are respectively conducted,the temperature performance of power battery has been summed up to provide theoretical basis for the thermal management strategy.(3)The thermal management system at home and abroad is summarized,and a thermal management strategy based on internal estimation temperature is put forward.Based on the battery estimating equations of internal temperature,the estimation model of internal temperature has been built on Matlab/S imulink software to analysis of estimation error.The hardware and software framework are designed to provide support for thermal management system construction.(4)In order to verify the temperature performance of power battery,the experiment platform of thermal characteristics is built and the related test data is handled to get the relationship curve of SOC with open circuit voltage and internal resistance.Semi-physical test bench of the thermal management system is set up to improve the hysteresis based on the strategy of cell surface measuring temperature and verify the effectiveness based on the strategy of cell internal estimating temperature.