Research And Design On Energy Management System Of Lithium-ion Battery

Increasing depletion of oil resources and the environment pollution make the electric cars enter a period of rapid development. Lithium-ion battery has become the darling of the electric energy for its incomparable advantage of energy, volume, longevity, environmental protection and so on. But some problems such as the cost of lithium-ion battery, cycle life, and the using safe restrict the wide use of lithium ion battery. The lithium ion battery energy management system was put forward to solve the problem and it can display the real-time parts of the working parameters(voltage, current, temperature, charged state), and the operation personnel can easily acquaint the working state and make the best battery solutions and ensure the safe, reliable lithium ion battery pack, and the maximum cycle life of the battery.The electrochemical properties of lithium-ion battery was firstly introduced in the paper and part properties of the battery was tested and analysis though the open circuit voltage characteristic test, load voltage characteristic test, battery efficiency characteristic test and got the properties of the open circuit voltage,load voltage and charge and discharge efficiency. In order to timely estimate on-line the state of charge of the lithium-ion more accurate and convenient, combined with traditional ampere-hour integral method, the open circuit voltage and the load voltage method, incorporating the charging and discharging efficiency and temperature factor compensation measures. A new timely estimation method of SOC ampere-hour integral was proposed, and the SOC real-time simulation model is established, and the lithium-ion battery charge and discharge experiment platform to test the real time SOC estimation method. The simulation and experimental analysis results show that under the condition of constant current and the circulating current conditions, SOC varies within 3 percent; In the other two conditions, SOC estimation can real-timely reflect the current battery charged state. The conclusion is that the new ampere-hour integral real-time estimation method has a good theoretical feasibility and precision, and provides battery important reference value for SOC real-time estimation and detection.The achievement of Lithium-ion batteries energy management system functions must have hardware and software supporting, the lithium-ion battery energy management electronic control unit was designed with MC9S12XS128 as main control chip. Hardware modules mainly include the power supply designing, data acquisition circuit designing(acquisition circuit voltage, current acquisition circuit, temperature acquisition circuit designing), balancing control circuit designing, communication circuit designing(CAN communication circuit, serial communication circuit designing) protection circuit designing and display circuit designing. In software aspect, modularization program designing using C language programming, Writing debugging, compiling and linking complete program are based on Freescale CodeWarrior software, designing data collection routines, SOC calculation routines, balance control and CAN communication module subroutine subprogram. Finally I have designed and product the lithium-ion battery energy management system electronic control unit BMS.We have Build a lithium-ion battery energy management system performance test bench, including the power supply batteries, furnace, charger, lithium-ion battery pack. BMS developed by this paper and analyzed by a computer, etc. Then the SOC estimation test experiment of 15 A current conditions was conducted. The results show that the energy management system of the lithium-ion battery has better function and charged state estimation precision, stable running, and improve the lithium-ion battery performance effectively.