| Energy storage system, as a buffer of microgrid, plays an important role in the generation of renewable energy power. The energy storage system consists of Lithium iron phosphate lithium-ion battery. Aiming at making the full use of capacity of a battery and increasing its lifetime, we designed a battery management system (BMS) which adopt lithium iron phosphate power battery as the energy storage element. As a result, the BMS can control the battery charge and discharge, can estimate the battery status and capacity which will lead to an increased lifetime and stability of the battery.First, some concepts about lithium ion battery are introduced in this paper and the lithium ion battery working principle is analysed. And then, kinds of lithium ion battery equivalent circuit models are introduced. At last, the Thevenin equivalent circuit model is selected and parameters of this model are determined by the experimental data which is processed by algorithms in Matlab/Curve Fitting Tool toolkit. The good accuracy of estimation SOC can be proved by using the battery model built in Matlab/Simulink and the algorithm of least squares support vector machine(LS-SVM).The function of the battery management system is introduced in detail and divided in several modules. Hardware of every module is designed, including the MCU module, the power supply module, the temperature collection module, the voltage acquisition module, the current collection module, the CAN module, The SPI module, etc. According to the function of every module, the corresponding electronic components are selected to finish the design of the hardware circuit of the battery management system. Sensor technology and signal processing technology and CAN communication technology and serial communication technology are all used in the BMS.Software of this system is designed based on the hardware circuit, including control of balancing Lithium Ion Battery, warning, charge and discharge control and battery pack state of charge detection etc. Finally, experiment is conducted to the battery management system. According to the process of the charge and discharge, the battery management system can meet the demands basically. |
