The Test And Application Research Of Li-ion Power Battery Dc Internal Resistance

The energy storage system based on lithium ion(Li-ion) battery is widely used in the field of electric vehicles. How to charge fast and analyze the consistency of Li-ion battery pack are problems urgently to be solved or improved, which ensures the cycle life and safety of Li-ion battery. To improve this situation, the main content and results of this paper include the following aspects:The temperature characteristics of the Li-ion battery parameters are researched based on Thevenin equivalent circuit model. In this part, this paper uses a certain parameter identification method to obtain parameters of the model under the different state of charge(SOC) and temperature conditions. Based on the analysis of the parameters temperature characteristics, it establishes a function of parameters on SOC and temperature.The temperature characteristics of the Li-ion battery direct current(DC) internal resistance is studied. Based on the experiment data of DC internal resistance, this paper has established a function of DC internal resistance related on SOC, current and temperature with curve fitting, interpolation and correction techniques. Simulation results validate the accuracy of the DC internal resistance function. This result can be applied to optimize the charging or establish a model with higher accuracy.A multistage constant current(MCC) charging method has been proposed in this paper. Based on the experiment data under the constant current working condition, this paper established a function of the Coulomb efficiency coefficient and an energy loss equation. This paper puts forward a MCC charging methed considering the Li-ion battery internal energy loss and charging speed, which considers the Li-ion battery cycle life.An experimental platform is set up and the consistency of the Li-ion battery pack is analyzed. According to the requirement of the battery pack on-line test, this paper has built the experimental platform for Li-ion battery pack. Based on the current and voltage data of Li-ion battery pack, the DC internal resistance of the battery pack is calculated. With the DC resistance data, the consistency of the Li-ion battery pack is analyzed and the monomer battery with poor consistency can be easily picked out in order to facilitate the timely replacement.