Design And Research Of The Battery Energy Management System For Hybrid Electric Vehicle

Under the pressure of the scarcity of oil source and environment pollution, to be dedicated to the strategy of sustainable development, Hybrid Electric Vehicle(HEV) has become an important consideration in the twenty-first century. All specialists in whole world have agreed on this: the application of Hybrid Electric Vehicle is not a transition phase, but be a new revolution of Automobile industry.Because the service life of NiMH battery is limited and the running circumstances of HEV are considerably complex, which influences the service life of battery. It is very essential to detect and control battery in order to ensure the performance and prolong the service life. But it is a problem about how to detect and control NiMH battery in the developing process of HEV. Up to now, this technology is still researching and developing.NiMH battery is selected as power battery used in HEV based on the current level and the developing process of battery in the paper. And then a detailed analysis of the state of charge(SOC) is analysis is provided, including evaluation methods and impact factors. Based on fast charge theory, the changing situation of charge voltage and current with time, which is the directly impact factor of SOC, is researched in experimental method. The range of current is also been ascertain in charge-discharge efficiency experiment, which is one of the current control objectives of battery management system(BMS).Based on the functions and the requirements of BMS, the circuit of battery checkers and control systems are designed in the paper, including voltage conversion, main controler, date collection and detection, equalize circuit and so on.After the analysis of several types of common NiMH battery models, PNGV is chosen. At the same time, in order to alleviate the problems when using Ah counting method to estimate SOC: the initial SOC, Coulombic efficiency are difficult to measure, a new estimation method combined Kalman filter and Ah counting method is used and an equivalent Coulombic efficiency is defined. Finally, laboratory testing confirm the truth of the estimate precision requirement of HEV.