Switching and Conduction Loss Reduction of Dual-Buck Full-Bridge Inverter Through ZVT Soft-Switching Under Full-Cycle Modulation

Based on the no blanking time characteristic, voltage error does not occur in the pulsewidth modulated output stage of dual-buck full-bridge inverter (DBFBI), resulting in lower total harmonic distortion (THD) of the output current. The two main modulations applied in the topology are half-cycle modulation and full-cycle modulation. Compared with the half-cycle modulation, the full-cycle modulation does not have the zero-crossing problem, but the inverter requires a bias current to guarantee better output waveform. The circulation current loop caused by bias current has a great influence on inverter efficiency. This article proposes a novel zero voltage transition (ZVT) soft-switching topology to increase efficiency by reducing the switching losses and conduction losses resulting from low bias current. The advantages of the DBFBI are included in the proposed inverter. The soft-switching condition is achieved by the snubber cells, and the energy stored in the passive snubber capacitors can be transferred effectively. The topology deduction, operating principles, and design guidelines are presented in detail. An 800-W experimental prototype operating with a 100-kHz switching frequency is implemented to verify the theoretical result.