High efficiency DC-DC converter using a series-parallel compensation method for a fuel cell

This paper proposes a novel DC-DC converter for a hybrid power supply using both a fuel cell and a battery. In the proposed circuit, the power converter with the battery is connected in series to the fuel cell. The output voltage is controlled by a series converter that regulates only the differential voltage between the fuel cell voltage and the output voltage. The power rating of conventional buck-boost DC-DC converters are dominated by the input voltage or the output voltage. In contrast, since the voltage rating of the proposed circuit requires the differential voltage between the fuel cell voltage and the output voltage, the power rating of the proposed circuit is smaller than that of the conventional converters. In addition, in order to suppress large current ripple in the fuel cell, a parallel converter is added to the series converter. The experimental results confirmed that the proposed circuit could achieve 98.8% at the maximum efficiency point in the small differential voltage region.