Characteristics And SOC Estimation Of Ni-cd Battery For Rail

To ensure the safe and reliable operation of the rail in an emergency,the battery is essential as a backup power source.To ensure that the battery is ready for working,reliable battery management should be performed.In the battery management system,the state of charge is an important indicator,but the estimation is more severely affected by the ambient temperature and discharge rate,which makes it more difficult.Based on the study of battery charge and discharge characteristics,using the design of the equivalent model o f nickel-cadmium battery,the improved extended Kalman filter estimation method is used to accurately estimate the state of charge of the battery.By studying the charge and discharge characteristics of nickel-cadmium batteries,a combination of Peukert equation and p iecewise function fitting was proposed to estimate the available capacity of the battery.The experimental results show that the method has higher estimation accuracy under different discharge rates and temperature conditions.On the basis of characteristics of nickel-cadmium battery,the equivalent circuit model based on second-order RC nickel-cadmium battery is designed by comparing different battery equivalent circuit models.Through t he improved cyclic pulse experiment,the model parameters of the battery under di fferent state of charge were obtained.The identified parameters are brought into the simulation model,and the feasibility is verified by simu lation.In order to accurately estimate the state of charge of the battery,an improved extended Kalman filter algorithm is designed by using the established equivalent circuit model.This method overcomes the problem that the system may cause the filter to diverge when the system state is abrupt or the model is nonlinear.Simulation results show that the proposed me thod improves the estimation accuracy.The experimental verification platform of the system was built.The voltage and current of the battery were collected,and the improved extended Kalman filter algorithm was used to verify the discharge experiment unde r different temperatures and rates.The experimental results show that the estimation method fully meets the requirements.