Research On The Estimation Of SOC In Lithium-ion Battery Based On Sliding Mode Observer Method

In many energy conversion process, batteries play act as a "bridge" role in various aspects of the use of energy as a form for conversion efficiency and equipment conditions unique advantages. Batteries has been widely used as one of the most common electrical energy storage devices which can provide stable power in long period time. State of charge of battery(remaining capacity) is an important secondary volume which can not be directly measured, it can make great difference in accurate estimate to extend battery life and improve the utilization efficiency.Although most current SOC of battery estimation methods can be able to achieve requirements of fast measurement, but ignores the battery electrolyte diffusion impact on the battery SOC caused by the transient estimated response. Sliding mode observer based on method control theory which takes the transient response of the cells into consideration by the equivalent model to estimate the battery SOC state space model to construct the corresponding equivalent circuit model through the battery, thereby improving the battery model can improve the rationality the accuracy of the results. In this paper, lithium-ion batteries which are often used as vehicle energy source as the research object, specifically as follows:1. The paper chooses lithium-ion batteries for the study, the need for lithium-ion battery works, features and during operation of the battery SOC to make a statement obtained and analyzed in the estimation process of the lithium-ion battery SOC accuracy Several factors influence.2. On the basis of the common lithium-ion SOC estimation methods, after the comparison of the scope and the corresponding advantages and disadvantages of several different estimation algorithms and battery equivalent circuit model, the equivalent circuit to improve transient response links with SOC estimation method proposed sliding mode observer equivalent model and improved binding.3. With the relation in open-circuit voltage and SOC, RC equivalent circuit model parameter identification to determine the battery model parameters for circuit verification experiment using dynamic conditions test method, that judgment after the battery model parameter identification voltage at different points in time whether the error is to determine the feasibility, within reasonable limits, to lay the foundation for subsequent experiments.4. Designing lithium-ion battery system such as parts of the hardware circuits and software flow charts. Then try to test and verify the validity and reasonableness of estimation methods by the recorded results, which show that the method can improve the estimation accuracy of SOC.In this paper, it is not limited to lithium-ion batteries for electric vehicles with simple method, in other types of electric vehicles, but details and other factors can also be applied after promotion to be resolved.