Performance Evaluation of Future T-Type PFC Rectifier and Inverter Systems with Monolithic Bidirectional 600 V GaN Switches

Three-phase PFC rectifier and inverter systems can be realized using identical main converter stages (MCSs) that comprise three three-level T-Type (TT) bridge-legs and a DC-bus referenced LC-filter stage. TT bridge-legs advantageously realize three output voltage levels by extending a half-bridge with the possibility to connect the switch node to the capacitive DC-link midpoint. To do so, a switching device with bipolar voltage blocking and bidirectional current carrying capability is required. A novel monolithic bidirectional 600 V/140 mΩ GaN e-mode transistor is an ideal candidate to realize the required midpoint connection in a chip-area efficient way. We therefore comprehensively characterize this monolithic bidirectional switch (M-BDS) in an 800 V DC TT bridge-leg realized with two additional 1200 V/140 mΩ SiC MOSFETs. Continuous operation of the M-BDS in all four voltage/current quadrants is demonstrated at ±400 V, and results of calorimetric measurements of the hard- and soft switching losses are provided. This facilitates the evaluation of the TT MCS’ achievable performance in CCM and TCM rectifier and inverter designs regarding efficiency and power density. For MCSs with (three-phase) nominal power ratings of up to 2 kW, we find efficiencies of > 99 % for power densities of up to about 15kW/I.