Owing to high oil prices and the efforts to reduce greenhouse gases according to the United Nations Framework Convention on Climate Change, there has been active research and development on environmentally friendly, high-efficiency vehicles. In developing the system design and specifications of an environmentally friendly vehicle, various simulations have been performed on the different components and the overall system. Although a precise modelling of each part and the system as a whole is necessary for an accurate simulation, detailed modelling of a high-capacity battery systemwhich directly affects the performance of an environmentally friendly vehicleis difficult to achieve owing to the non-linear electrochemical properties of the battery. In this study, an electrochemical impedance measurement technique is used to implement a battery cell model, upon which a battery system model for environmentally friendly vehicles that takes into account the ancillary components of the battery pack is developed. And we used an actual battery system that requires complex and difficult modelling owing to non-linear and irreversible properties of the battery. In addition, to verify the developed battery system model, we used models implemented for other vehicle components and systems to construct a hardware-in-the-loop simulation of a battery reflecting an actual driving environment.

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The ultracapacitor module has recently been recast for use in hybrid energy storage systems (HESSs). As a result, accurate state-of-charge (SOC) estimation for an ultracapacitor module is as important as that of primary sources in order to be utilized efficiently in an energy storage system (ESS). However, while SOC estimation via the open-circuit voltage (OCV) method is generally used due to its linear characteristics compared with other ESSs, this method results in many errors in cases of highcurrent charging/discharging within a short time period. Accordingly, this paper introduces a dynamic SOC estimation algorithm that is capable of SOC compensation of an ultracapacitor module even when there is a current input and output. A cycle profile that simulates the operating conditions of a mild-HEV was applied to a vehicle simulator to verify the effectiveness of the proposed algorithm.

leebh@katech.re.kr increases the number of engine ignition almost 10 times more Abstract -To improve the cycle life and efficiency of an energy than the conventional vehicle. Since the ignition energy must storage system for 11EV, a dynamic control system consisted of a be delivered from the energy source of the vehicle, if it is switch between battery and ultracapacitor module and a