Digital control of an isolated active hybrid fuel cell/Li-ion battery power supply

One of the important issues in modern electronic equipment is providing higher peak power while preserving high energy density. Hybrid power sources composed of fuel cells and batteries combine the high-energy capabilities of fuel cells with the high-power capabilities of batteries. DC/DC power converters can appropriately control the power flow shared between the fuel cell and battery system. In this paper, we propose a new implementation of hybrid fuel cell/battery systems. A 50-W isolated power electronic interface system for a hybrid solid-oxide fuel cell (SOFC/Li-ion battery portable power supply is designed and implemented. The control strategy presented in this paper is able to regulate the output current of the fuel cell, the charging current of the battery, and the output voltage of the power supply. The control strategy is implemented in a DSP and tested by simulation and experiments. Experimental results present the flexibility and generality of the control strategy.