A new utility-scale power converter for large fuel cell power plants with individual stack power control

In this paper a new utility scale power converter for large fuel cell power plants with individual stack power control is presented. The proposed converter topology allows for multiple fuel cell stacks to be referenced to ground, connected via high frequency isolation to a single multilevel inverter interface to utility. The topology incorporates a unique power sharing converter that enables each fuel cell output power to be individually adjustable. It is shown that four 250-kW fuel cells are operated at various power levels, ranging from 20% to 100% power sharing and connected to a single 3-level NPC inverter interfaced to the electric utility. Altogether, this new fuel cell - power sharing converter (FC-PSC) design will increase power sharing capabilities, output power, efficiency, thermal balancing, system versatility, and significantly lower power conditioning costs for utility fuel cell power systems. Experimental results from scaled-down laboratory prototype are shown to validate FC-PSC operation.