Research And Design Of Intelligent Control System For High Power Battery

The battery control system,as the key technology of battery development,includes the collection of information such as current and voltage,information communication,human-machine interface,estimation of the state of charge(SOC)and balanced management system.However,the design and research of the battery SOC and balance system have become the research problem of the system at present.The breakthrough of these two problems is also the key to improve the battery efficiency,increase the cycle life of the battery and make the battery run stably.First,in this paper,author conducted battery charge and discharge experiments based on reading a lot of literature on the development prospects of the battery in-depth understanding,and understood more profoundly through the experimental data of lithium iron phosphate charging and discharging voltage characteristic curve,equivalent internal resistance changes,Open Circuit Voltage(OCV)and residual SOC,and the hysteresis curve of battery charging and discharging voltage,thus providing solid experimental data and theoretical basis for the next research.Second,in this paper,an original three-order RC electrical model has been designed and the mathematical characteristic of the model has been studied after comparing the advantages and disadvantages of a large number of battery models.Finally,in order to avoid the problem of "data saturation" produced by recursive least squares method,the least squares method with forgetting factor is used to identify the parameters in the electrical model.This model is better than the second-order RC cell model in characterizing the battery,method of estimating SOC adopted in this paper relies greatly on the battery model,so the accurate battery model is the key step to estimate the SOC.Thirdly,based on the more accurate battery model researched above,SOC estimation based on sampling point Kalman joint algorithm is used in this paper,at meantime of using lower system resource,this paper not only uses improved time integration method to estimate real-time battery power,but also uses the sampling point Kalman algorithm to correct the SOC estimation error when the error accumulation of improved integration method is too large.Finally,based on the research of various equalization systems,the design of equalization circuit is completed on the basis of the flyback type synchronous circuit.The fuzzy logic PID is used to control the duty cycle of the MOSFET in the battery equalization circuit,so as to realize the fast equalization of charge and discharge current control.At the same time,the unbalanced estimation algorithm is used to estimate the unbalanced cell,and intentionally overcharge and over discharge.These two improvements not only improved the equilibrium speed,but also made the state of the battery to maintain a longer time,thus making the balancing efficiency of the battery more prominent.