Study On Power MH/Ni Battery Management System

The power batteries for hybrid electric vehicles (HEV) are considered to be the green project in the 21st century, which can solve the problems of pollution and energy shortage caused by combustion engines. But the research and development of the technique and the relevant investigation of power batteries is a barrier for popularization and application of the electric vehicles.This thesis is worked on the SOC of battery management system. The prediction of discharge capacity of MH/Ni battery is a main part of battery management system.The exact and reliable SOC of estimation for battery is necessary for the battery management system in HEV, it is the key of practical of HEV. Since the actual SOC of MH/Ni battery is influenced by many factors, such as temperature, cycle of discharge and aging of battery, it is difficult to obtain ideal results by traditional methods. The application of Fuzzy logic method for the SOC estimation is described. The research achievements and innovations in this paper are as follows:Having analyzed the electronic mechanism of the MH/Ni batteries during charge and discharge, compared the advantages of MH/Ni batteries with other kinds of batteries, the results is that MH/Ni batteries is the promising power battery for HEV due to its advantages such as high power lever and long life.Principle of the reaction of the MH/Ni battery, the characteristics and existed problems of different kinds of SOC measuring methods are compared, such as use voltage or resistance of the batteries to get the SOC, then put forward the way of Fuzzy logic to estimate SOC of the batteries in this research. Modeling experiments show that, it is a new way to estimate SOC, but its drawback is unavoidable such as the designation of fuzzy membership function and fuzzy rules.In order to estimate SOC effectively, ANFIS(Adaptive Neural-Based Fuzzy Inference System)is a good solution which avoids the shortcomings of designing fuzzy membership function and fuzzy rules subjectively. The experiments show the model performance is satisfied, therefore, it points out a new way to resolve the prediction of MH/Ni batteries'SOC.