Inductor feedback ZVT based, low THD single phase full bridge inverter with hybrid modulation technique

This paper proposes a topology based on zero-voltage-transition (ZVT) technique to realize zero-voltage-switching (ZVS) for all the main switches of the full bridge inverter, and inherent zero-current-switching (ZCS) for the auxiliary switches. The advantages of the strategy include the provision to implement zero state modulation schemes such as unipolar or hybrid PWM scheme in the full bridge inverters to decrease the inductor current THD, naturally adaptive auxiliary inductor current and elimination of need for large balancing capacitors. The modulation scheme and the commutation stages are analyzed in detail. The whole inverter including the auxiliary ZVT branch is modelled. Finally a 1 kW, 400 kHz switching frequency inverter of the proposed topology using SiC MOSFETs has been built to validate the theoretical analysis. The ZVT with hybrid modulation technique is implemented in DSP TMS320F28335 resulting in full ZVS for the main switches in the full bridge inverter. The proposed scheme can save up to 32 % of the switching loss compared with no ZVT case.