Battery Equalization Management System Based On DSP

In recent years, li-ion batteries are widely used and applied for its large energy density, high working voltage, low self-discharge rate no memory effect. However, a battery management system is requested to prevent over-voltage and over-current for high activation of Lithium. This paper studies li-ion batteries in series mainly. In it, using SOC as a reference for battery equalization is presented and the battery management system in digital control based on DSP is researched.Firstly, this paper will introduce the background and the development of the Li-ion battery and battery management system. Secondly, the characteristics and the working principle of the li-ion battery, the charge-discharge characteristics and the charging method of the li-ion battery, and the common topology and the reference of equalization for the charge-discharge of li-ion batteries in series are introduced detailed. And based on which, we put forward the reference of SOC for battery equalization. Then, this paper will builds model, design and simulate circuit to the system of battery equalization management, and based on which, make the battery management system in digital control based on DSP.The battery management system uses SOC as the reference. At first, the system detects the SOC of every battery ceil. Then, using the maximum SOC as the reference, the equilibrium module charges the battery whose SOC less than the reference, which is called the equalizing charge. A constant voltage mode is applied in the equalizing charge based on the characteristic of the relation between the voltage and the residual capacity of Li-ion. The main chip of the battery management system in digital control is DSP in TMS320LF240X series. In the precess of design for the battery management system in digital control based on DSP, we gain mathematical model of flyback by small-signal modeling firstly. Then, design digital controller using a indirect design method. Finally, write control program according to digital controller to realize digital control of battery management.The paper mainly includes the finished work of the following sections: (1) In-depth research on li-ion battery and its management system:the characteristics and the working principle of li-ion, the charge and discharge characteristics and the charging method of the li-ion battery, the topology and the reference of equalization for the charge-discharge of li-ion batteries in series and its control scheme;(2) Equalization model is built up, control compensator for equalization is design, and modeling and simulation using simulink is applied.(3) Application of matlab/simulink to battery equalization management system modeling and simulation, implements the analog control of the equalization system of the battery in series, realized the equalization control and management based on DSP2407of li-ion battery system in series.