Design And Implementation On Energy Management System Of AGV Battery

Automated Guided Vehicle(AGV)is an unmanned carrier,which is equipped with battery and automatic guidance system.AGV,which has unique advantages such as security,flexibility,high efficiency,reliability and so on,meets the requirements of flexible manufacturing system,flexible assembly system and automatic warehouse.AGV is widely used in logistics system,such as post office,port,food,chemical,tobacco and other dangerous industry.Battery Management System(BMS)is a crucial part of AGV.The system plays an important role in safety,steady and reliability of AGV.Lithium-ion battery with an unparalleled advantage is gradually applied to AGV instead of the lead-acid and Ni-MH cell.Although there is a lot of research and application of BMS in electric vehicle,notebook,camera and so on,but battery technology and material optimization can't solve all problems in the use of lithium.AGV has its own characteristics on charging and discharging,estimation of SOC,heat management and balanced strategy,so it is vital to study BMS of AGV.This topic designs a BMS according to AGV specific requirements.The research work is as follows:(1)Analyze and demonstrate the function requirements and technology scheme of AGV battery management system.The type of the lithium battery is determined by the analysis of the common lithium battery.The method of detecting single cell voltage is selected by comparing the detection methods of single cell voltage in series.Based on the comparison and analysis of the conventional battery equalization methods,a suitable equalization method is chosen.Advantages and disadvantages of SOC estimation are compared,which can be used as reference for the subsequent SOC estimation.(2)The study of battery configuration.The reliability of usual battery pack attended modes and the influence on battery inconsistency were analyzed· It is found that the reliability of parallel-series structure is higher than series-parallel.The main factor separation and total factor separation were carried out for the single cell by using factor analysis and system clustering function of SPSS.The comparison result shows that the factor separation method performs better in improving battery consistency.(3)The SOC estimation of battery pack is studied.This paper puts forward an estimation strategy of SOC.The strategy combines open-circuit voltage estimation with Ah integral estimation,then considerate influences of discharging rate,cyclic life and temperature.The specific values of the parameters in the SOC estimation model are obtained by the experimental method.MATLAB/Simulink is used for simulation analysis and a lithium experimental platform is built to validate the estimation method of SOC.The results show that the SOC estimation error varies within 5 percents.(4)The design of hardware and software for AGV battery management system.Modular design concept is throughout the hardware.The design of the main control module,power module,data acquisition module,communication module,protection module,equalization module and memory module are described in detail.In software,UCOSII is used for single chip microcomputer to meet the real-time requirements.Computer software is designed with Microsoft Visual Basic 6.0,which achieves a number of functions,such as user verification,data display,parameter setting and,etc.(5)The performance test and field test are carried out to inspect the AGV battery management system.The results show that the system works stably and reliably.The system can collect the data of current,voltage and temperature accurately,estimate SOC accurately and the performance of the system achieves a predetermined value.