Loss evaluation of a series-parallel compensation DC-DC converter for a small fuel cell system

This paper proposes a novel DC-DC converter for hybrid power supplies using both fuel cell and battery. The output voltage is controlled by a series converter that regulates only the differential voltage between the fuel cell voltage and the output voltage. Although the load condition is changed, the variation of the fuel cell current is suppressed by a battery through operation of the parallel converter. The experimental results confirmed that the proposed circuit could achieve maximum efficiency point of 98.8% in the small differential voltage region. In addition, the loss analysis clarified the relations among the ripple current of the inductors, the inductor voltage and the inductors losses. As a result, it is confirmed that the proposed circuit achieves the minimum loss of the copper loss and the iron loss in the inductors when the differential voltage is small.