With three different DC-side and AC-sideconnections, the three-level H-bridge voltage source converters(3L-HB-VSCs) are alternatives to 3L neutral-point-clampedVSCs (3L-NPC-VSCs) for interfacing large wind turbines withelectricity grids. In order to assess their feasibility for largewind turbines, they should be investigated in terms of powerdensity, which is one of the most important design criteria forwind turbine converters due to turbine nacelle space limitation.In this study, by means of the converter electro-thermal modelsbased on the converter characteristics, the power capabilities,DC capacitor sizes, converter cabinet volumes of the three 3LHB-VSCs utilizing press-pack IGBTs are investigated in orderto quantify and compare the power densities of the 3L-HB-VSCsemployed as grid-side converters. Also, the suitable transformertypes for the 3L-HB-VSCs are determined and comparativelystudied in terms of volume and weight in order to estimate thesize effects of the 3L-HB-VSC topology on the whole windturbine connection system. Finally, based on the power densityand transformer-size investigations, the feasibility of each 3LHB-VSC is discussed.