Efficiency comparison of 2- and 3-level inverter based Power Conditioning System for grid-connected SOFC application

An efficiency comparison of 2- and 3-level inverter based Power Conditioning Systems (PCSs) is presented for a grid-connected Solid Oxide Fuel Cell (SOFC) application. The power conditioning systems examined are: an intermediate boost converter integrated with a 2- and 3-level inverter. The aim is to determine which power conditioning system yields the highest efficiency in terms of power losses of the semiconductor devices with a predetermined operating condition. In view of this, a relation between the fuel cell operating condition and power loss is established to evaluate the efficiency of the system. The power loss model presented in this paper has taken into account the conduction and switching losses of the semiconductor devices within each power conditioning system. Simulation results are presented showing the power loss characteristics with the operating condition. Finally, with regard to the global efficiency for the power conditioning systems, an intermediate boost converter integrated with a 3-level inverter is found to be the most favourable choice considering the typical operating condition encountered by a fuel cell at the kWatt level.