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This paper presents a new numerical simulation method to calculate transient voltage profiles of lithium-ion secondary batteries. The method employs circuit analysis of an internal equivalent electric circuit composed of an electromotive force, an LR parallel circuit, and eight CR parallel circuits. To demonstrate the accuracy and versatility of this approach, the authors measured the transient voltage responses of three types of test batteries with different output power densities, and compared these experimental data with simulation results. Battery performance was tested using different charge/discharge current patterns and a range of values for state of charge (SOC) and operating temperature. The accuracy of the proposed simulation method was confirmed for all test cases using the three different batteries and charge/discharge current patterns, demonstrating that the method is versatile and applicable to various lithium-ion secondary batteries regardless of type. Since the employed internal equivalent electric circuit is composed of only DC voltage source and linear R , L and C elements, all of general purpose software for electric circuit simulations can easily deal with the circuit. This advantage and the obtained results indicate that the proposed simulation method is a useful technique and offers a powerful tool to develop sophisticated battery control systems for various applications. [ABSTRACT FROM AUTHOR]

Abstract: The authors propose a solid oxide fuel cell (SOFC) co-generation system integrated with an electric vehicle (EV) charging station. To examine the feasibility of the proposed system, the authors numerically simulated the operation pattern of the proposed system, using the electric and thermal demands measured at a multifamily apartment from May 2003 to April 2004. Based on the simulation results, the authors calculated the overall efficiency of the system as well as the primary energy saving rate. The available electric energy for EV charging was also evaluated for the case of the proposed system installed in the multifamily apartment. As a result, it is made clear that the annually averaged overall efficiency reaches about 77% (LHV) and the expected primary energy saving rate exceeds 30% throughout the year. In addition, it is also found that sufficient amount of electric energy for EV charging can be obtained from the proposed system. Therefore, it can be concluded that the proposed SOFC system can successfully combine electrical/thermal energy co-generation and electric vehicle charging while maintaining high energy efficiency and good matching to energy consumption patterns. [Copyright &y& Elsevier]