Fuel Cell Based Battery-Less UPS System

In this paper, new battery-less UPS system configuration powered by fuel cell is discussed. The proposed topology utilizes a standard standby UPS module and the battery is replaced by a supercapacitor. The proposed system operation is such that the supercapacitor bank is sized to support startup and load transients and steady state power is supplied by the fuel cell. Further, the fuel cell runs continuously to supply 10% power in steady state. In case of power outage, it is shown that the startup time for fuel cell is reduced and the supercapacitor bank supplies power till the fuel cell ramps up from supplying 10% load to 100% load. A detailed design example is presented for a 200 W/350 VA 1-phase UPS system to meet the requirements of a critical load. The equivalent circuit and hence the terminal behavior of the fuel cell and the supercapacitor are considered in the analysis and design of the system for stable operation over a wide range. Experimental results along with stability analysis and performance verification of the entire system have been shown in this paper.