AC Small-signal Modeling Of Lithium-ion Batteries And Applications

Since the advent of lithium-ion batteries, because of its unique advantages of high specific energy and no pollution, they are favored by people and gradually replace other types of batteries. With the rise of new energy industry, large-scale lithium-ion batteries are used in energy storage system and power system. How to efficient safety management of battery becomes an inevitable question. And the nonlinear of lithium-ion increases the difficulty of the battery system. Battery model, as the battery internal reaction mechanism of the representation and the embodiment of the external performance, became the basis of battery management system.There are many lithium battery models and different battery system has different model of the battery. The traditional test method for parameter identification according to the HPPC (Hybrid Pulse Power Characterization) of lithium battery not only should choose the suitable model but also needs to accurate and determine the load voltage at that moment. These have brought some problems for parameter identification.According to that, a small signal model of the battery was set up by using EIS (Electrochemical Impedance Spectroscopy) which is commonly used in electrochemical analysis. A small amplitude perturbation of communication signal was applied on both sides of the battery system which is under test. Then the method of the system response can be observed. The equivalent circuit model of the battery can be built according to the figure of the frequency to the equivalent element.The Levy, which is usually used in control field, was used in this article to identify the parameters of the battery model in model parameter identification. The Levy, which is based on the least square method, weighted the error criterion. So that the error criterion can be switched from a nonlinear minimization problem into a linear minimization problem. The AC small signal model parameters are basically remained unchanged when the battery charged status to between 10% to 90%. This conclusion depends on the analysis to each parameter of the small signal model of battery.This paper using the AC small signal model and its parameters to design parameters for the battery charging device in identification of model parameter. It can ensure that the device has better stability and dynamic characteristics. The control system of the device has good robustness by experimental verification.