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The wind turbine converters demand high power density due to nacelle space limitation and high reliability due to high maintenance cost. Once the converter topology with the semiconductor switch technology is selected, the converter power density and reliability are dependent on the component count and the switch thermal performance which is determined by the converter load profile and the converter structure. In this study, the converter-structure based power loss and thermal models are developed for the medium voltage full-scale 3L-ANPC-VSC and 3L-HB-VSC utilizing press-pack IGBT-diode pairs and interfacing a 6MW wind turbine to a medium voltage grid. The switching power loss models are built using the experimentally obtained switching power loss data from a full-scale 3L-ANPC-VSC leg. The static thermal models are developed considering the double-sided cooling of the switches by the cooling plates. For the experimental model verifications, a test setup with a single-phase full-scale 3L-ANPC-VSC is introduced. Using the power loss and thermal models, the switch junction temperatures are obtained on simulation for the wind turbine grid interface. The power density and reliability of the VSCs are discussed and compared with respect to these junction temperatures as well as the counts of press-pack switches, gate driver, and cooling plate.