Research And Design Of The Monitoring System For Lithium Battery Based On Embedded

With the dwindling of the non-renewable resources and increasing environmental pollution, the use of new energy is more and more important. Lithium ion battery is more and more widely used in everyday life, Due to the advantages such as environmental protection, long life and low self-discharge rate, Lithium ion batteries now have replaced the the commonly used high pollution type batteries. As the power source of hybrid cars lithium ion battery is popular around the world, while the battery life of lithium-ion batteries are short, thus it has been as a topic in our country "863" plan project. The battery monitoring system is mainly used to monitor the voltage, current, temperature and the residual capacity of battery in real-time and prevent the battery overcharge,discharge and exorbitant temperature so as to produce warnning information and control it, etc).A good battery monitoring system not only can monitor real-time data, but also can play a battery of optimal performance while protecting cells,it can also prevent unsafe situation occurring prolong the service life of battery thus to reduce the cost of the battery, etc.At first, this paper mainly introduces the development history and status about battery monitoring system at home and abroad, and describes the significance of battery monitoring system, and analyses the characteristics of the characteristics of existing battery monitoring system, and puts forward some innovative points due to the existing technology. Secondly it introduces the proposed battery monitoring system of the whole structure. This article mainly adopted Altera corporation CycloneII series FPGA as the main control chip, and adopts the technology of SOPC system on building a set of feasible, reliable, economic battery monitoring system.This paper introduces the SOPC embedded system configuration of the required components and interfaces, and analyzes the AD interface and AVALON bus based on embedded system, and gives the both compatible design ideas. Then it introduces the meaning of SOC estimation and estimates the difficulty and key, analyzes the advantages and disadvantages of the existing estimates strategy, and combines the existing several SOC estimation strategy to a new SOC estimation method in this paper, and expounds the derivation process of the kalman filtering algorithm and compound kalmanfiltering method.We make open circuit voltage method,ampere-hour integral method and the extended kalman filtering method in combination to form the SOC estimation.Firstly, and the open circuit voltage method is adopted in cell open circuit static state estimate SOC, this method accuracy is higher, the second using Annintegral method, got in front of the initial value of SOC by ampere-hour integral method in the battery working state of SOC estimation is simple, reduces the operation pressure of MCU, the battery working state SOC affected factors more ampere-hour integral method of estimating accuracy will be increased with the increase of using time is reduced, through the kalman filtering method for SOC correct, so as to provide an ampere-hour integral method, the optimal estimate the initial value. Behind and mainly introduces the FPGA based around the battery monitoring system of the peripheral circuit design includes power supply, clock reset, memory control circuit and data acquisition and communication circuit and analyzes the circuit design of circuit diagram is given. AD data acquisition chip is used in the design of ADI company launched two years ago the battery monitoring system chip AD7280 A, analysis the advantage and function of the chip to use and designed a high-precision battery information collection system and battery equalization circuit. Through analyzing the hardware and the function of the system, and emphatically introduces the embedded system software design method and process, mainly is the SOC estimation subroutine processes, AD sampling process, and communication software design process.Finally through the simulink composite kalman filter method to estimate the effect of SOC, analysis the advantages and disadvantages of this estimation method, and gives the system test results to verify the function of the system implementation.