An interleaved step-up/step-down converter for fuel cell vehicle applications

Fuel cells have received considerable attention as one of the most promising candidates for green power sources in vehicles. The voltages of fuel cells vary widely depending on the operating conditions. Furthermore, the output power of the fuel cell in a vehicular powertrain should be controlled in accordance with some energy management strategies. For these reasons, the fuel cell must be interfaced with other components by means of a DC/DC converter in fuel cell vehicle applications. A step-up/step-down converter for fuel cell vehicle applications, which effectively operates in step-up or step-down mode when the fuel cell voltage is lower or higher than the output voltage of high-voltage direct current bus, is proposed in this paper. To reduce the current ripple, the interleaved circuit structure is used for the proposed converter. The proportional-integral regulator for the fuel cell current control is achieved by a digital signal processor to improve the reliability and flexibility of the converter. Smooth transition between step-up and step-down modes is realized using average current method for the converter. The principle of operation and theoretical analysis of the converter are given. Experimental results of a prototype are provided to evaluate the performance of the proposed scheme.