Multicascoded Sources for a High-Efficiency Fuel-Cell Hybrid Power System in High-Voltage Application

This paper presents a high-efficiency multicascoded hybrid power system for high-voltage application. For a cascoded configuration, the source is serially connected to the output terminal of a converter to increase the voltage conversion gain by one. In addition, parts of the energy from the sources are supplied directly to the output load with high-efficiency features. Based on these, a three-cascoded hybrid power system integrating the fuel cell (FC), battery, and ultracapacitor module is presented. A two-loop active FC control strategy is proposed to manage the power flows of the proposed system. The whole efficiency and hybrid power flows of the multicascoded system are discussed and demonstrated under different hybrid situations. Finally, the experimental results from a prototype circuit of the FC hybrid power system show that the hybrid system can provide 200 V of output voltage, 500 W of rated power, and about 1 kW/25 min long-term overload power. In addition, the whole efficiency of the proposed hybrid power system can achieve 93.6%.