SOC Estimation Of Battery Pack For Electric Vehicle

Since reform and opening up, the car accelerated production promoted the rapid development of social economy, at the same time the car consumption and emissions have also led to massive pollution of ecological environment, global temperatures rise generally, therefore, to develop in the direction of green energy saving become the main direction of automobile technology. In recent years, countries have realized the new energy vehicles for the prospective significance of social development, with its instead of the traditional internal combustion engine vehicle research has always been the focus of all walks of life.At present, the development of each type of new energy vehicles have a large market for its economic basis, the demand of the market scale is very substantial, as an important part of new energy vehicles, electric vehicles has been the strong support and development of state, has huge advantages and broad prospects for development.Battery is the core of the electric car parts, has been a research focus in the field of electric vehicles, in today's puts forward higher requirements on electric vehicles,electric vehicles need to break through the key issue of technology or battery,therefore improve the performance of the battery and its protection is very important.This paper introduces the working principle of lithium-ion battery, on the basis of the related experiment analysis of the lithium ion battery voltage characteristics and resistance characteristics, in order to do the battery modeling of the next step work also analyzed the factors that affect battery capacity. Based on Matlab and the recursive least square method for the tool, established the simulation model of the battery equivalent circuit model of parameter identification, and designs the model of constant current charge and discharge test. At the same time, the function relation between the open circuit voltage and SOC as a mathematical model of the battery, this paper analyses the basic principle of linear Kalman filter and extended Kalman filter.Finally, on the cell model are built to establish circuit equation, thus it is concluded that the state of the system, the observation equation, according to the calculation process of SOC estimation algorithm, get the EKF in the form of linearization is derived after each iteration matrix, is established in the Matlab simulation model of the algorithm.