Research On On-line Monitoring System Of Lithium Battery For Hybrid Electric Vehicle

The light hybrid electric vehicle has been vigorously promoted due to its low fuel consumption and strong rangeability.The lithium-ion battery is an important power source of the light hybrid electric vehicle,and its state performance directly affects the safety and reliability of the vehicle.It is vital to monitor the working status of the vehicle lithium-ion battery.Battery state of charge(SOC)estimation is an important part of the battery monitoring system,which is of great significance for predicting mileage,optimizing battery charge and discharge,improving vehicle performance,and so on.Thus,this paper studies the online monitoring system of lithium batteries for hybrid electric vehicles,which can monitor the working parameters such as current,voltage,and temperature of lithium batteries in real-time,and estimate the SOC.Vehicle-related personnel can know the status of the battery in time to make correct judgments and decisions,to prevent vehicle accidents.The work done in this paper is as follows:(1)Introduction.This paper introduces the research background and significance of the subject deeply understands the research status of automobile power battery,SOC estimation,and vehicle online monitoring technology at home and abroad,and puts forward the main research content of this paper.(2)Performance analysis and SOC estimation of the hybrid electric vehicle battery.The working characteristics of lithium-iron-phosphate batteries are deeply analyzed,and the existing SOC estimation methods are studied.Based on the principle of unscented Kalman filter,combined with the temperature characteristics of the battery,an improved unscented Kalman filter SOC estimation method is designed and simulated on MATLAB,which can achieve high accuracy.(3)System scheme design and related techniques.This paper analyzes the functional requirements of the online monitoring system for lithium batteries of hybrid electric vehicles,puts forward the overall design scheme of the system,and introduces the related techniques involved.The system consists of two parts: the vehicle terminal and the online monitoring platform.The vehicle terminal displays the battery voltage,current,temperature,and other parameters collected on the local LCD screen,and transmits the data remotely through NB-Io T wireless communication technology.The online monitoring platform is used to receive and display the battery parameters uploaded by the vehicle terminal to meet the remote viewing needs of the relevant personnel.System-related technologies include a sensor,NB-Io T,and One NET cloud platform technology,and so on.(4)Vehicle terminal design.Design the hardware circuit of the vehicle terminal,including the selection of core components,functional module circuit design and analysis.The function module circuit is composed of power module,microprocessor,battery parameter detection circuit,LCD display screen and NB-Io T wireless communication circuit.The software program of vehicle terminal is designed,and the program design is carried out based on STM32 for data acquisition and processing,local display,NBIo T wireless communication and SOC estimation,and the program design flow is described.(5)One NET cloud platform design.This paper analyzes MQTT protocol,creates products and devices based on the One NET cloud platform,sets up data flow,and designs an online monitoring interface.(6)Experiment and analysis.This paper builds an experiment platform to test the functions of data acquisition,data transmission,online monitoring platform,etc.The experimental results show that the system can realize the collection,local display,and remote transmission of the battery parameters.Meanwhile,the online monitoring platform can display the corresponding data correctly,which verifies the feasibility of the system.To sum up,the system designed in this paper can realize the collection of voltage,current,temperature,and other parameters of hybrid electric vehicle lithium battery,SOC estimation,remote data transmission and viewing,and other functions.In addition,relevant personnel can check the battery status information online to make timely decisions and effectively reduce vehicle accidents caused by battery failures.