This paper presents the effects of introduction of residential polymer electrolyte fuel cell (PEFC) co-generation system with batteries in comparison with conventional systems that consist of a gas boiler and electric power from commercial grid, by computer simulation. The PEFC co-generation system in commercial use provides the average primary energy saving rate of 12.7% and CO 2 reduction rate of 15.4% with respect to the conventional system. Addition of 8.0-kWh batteries to the PEFC system results in limited improvements of 0.8 points and 0.9 points in the reduction rates, respectively, yielding 13.5% and 16.3%, when using a conventional operation planning method. A new operation planning method is proposed in order to make a precise control of charging and discharging the batteries. The average primary energy saving rate reaches up to 16.9% by the improvement of 4.2 points, and CO 2 reduction rate reaches up to 20.4% by the improvement of 5.0 points in the PEFC co-generation system with 8.0-kWh batteries using the new operation planning method. The new method can thus realize a substantial improvement in reduction rates. Furthermore, it is shown that the suitable battery module capacity for the residential PEFC co-generation system is 4.0 kWh.

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In the practical requirement for high efficiency, high power density, and high performance in switched‐mode power supplies and their related application systems, a variety of circuit topologies of dc‐dc converters incorporating soft‐switching PDM, PFM, and PWM control schemes have attracted special interest in low‐power and high‐power applications. Some types of quasi‐resonant soft‐switching PWM converters have remarkable advantages, such as lowered switching losses of power semiconductor devices, reduced dynamic electrical stresses, constant‐frequency operation, simple control schemes, and reduced EMI noise. However, most soft‐switched quasi‐resonant PWM converters developed so far include some inherent problems which must be solved, such as reduced power conversion efficiency due to significant circulating current generation. In recent years, a newly modified prototype soft‐switched PWM dc‐dc converter with a high‐frequency transformer link has been proposed, which is capable of excluding circulating current operation mode. This paper presents a novel high‐frequency transformer link soft‐switching PWM dc‐dc converter using active switches in the rectifier circuit. Its operating principles and unique features are described and compared with previously developed dc‐dc converters. The operating performance of this converter in the steady state is illustrated and discussed, including simulated analytical and experimental results. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(3): 81–93, 1997