Estimate And Realization Of Lithium Battery State-of-charge Based On Adaptive Kalman Filter

Recent years, the rapid development of our country’s economy,which leads to problems of environment pollution and energy shortage,has become a huge restriction for the development of the auto industry.Pure electric vehicles have become the trend of development of the autoindustry, because of its no emissions, low energy consumption, low noise,which can make environmental protection and relieve energy crisis.Power source, which is the core of the pure electric vehicle technologyand cost factors, is particularly important in the development of newenergy vehicles. Compared with other cells in the energy density, Lithiumion battery’s excellent comprehensive performance, including the energydensity, cycle life and so on, has become the primary choice of pureelectric vehicle power supply. Effective management technology forlithium battery has important significance to prolong the service life oflithium batteries, increases the energy utilization in power supply, andsolves the security problem in the process of use.The paper on the basis of analysis of lithium batteries owncharacteristic, here comparing advantages and disadvantages of manykinds of lithium ion battery circuit model, a second-order RC circuitmodel is put forward. Considering various factors, its mathematicalmodel of the circuit model is derived, and then put forward a moreaccurate battery charged state estimation method that adaptive filteringand the method of combining kalman filtering algorithm is adaptivekalman filtering algorithm, in view of the current variety of advantagesand disadvantages of lithium battery state of charged estimation method.Then a lithium battery management system was designed, thedistributed structure was used on hardware system that divided intomaster control module and unit module. The CAN bus building networkbetween the module, main control module is responsible for the control ofcharging machine, LCD display, thermal management and the estimate of state of charged. Unit module is responsible for the signal acquisition ofvoltage, current, temperature, and control the balance between monomerbatteries according to the information was collected. In the aspect ofsoftware system, transplantation uC/OS-II on main controller toimplement the task scheduling and management, which improve theprocessing performance of the system, and flow chart are provided for thesystem of software implementation, Lithium battery management systemhas strong anti-interference ability on hardware of circuit and have aaccurate result on the state of charge estimation battery.