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This paper presents a dual-buck full-bridge inverter (DBFBI) to solve the shoot-through problem in conventional bridge-type inverters and reduce the voltage stress of the power device in the dual-buck half-bridge inverter (DBHBI). Hysteresis current control is used in the DBFBI. All switches and diodes operate at each half line cycle, and the freewheeling current flows through the independent freewheeling diodes instead of the body diodes of the switches, so the efficiency can be increased potentially. As the shoot-through problem does not exist in the DBFBI, dead time between the switches need not be set. The input-voltage utilization rate of the DBFBI is twice that of the DBHBI under the same output-voltage condition, i.e., the voltage stress of the power device in DBFBI is half that in the DBHBI. The operating principle, stability and relative stability analyses, and design guidelines and example are provided. Experimental results of a 1-kVA DBFBI verify the theoretical analysis. The comparisons among other inverters and the DBFBI show that the proposed inverter is very promising in 220-240-Vrms output-voltage and high-reliability applications, such as uninterruptible power supplies and grid-connected inverters.
Date of Publication: Aug. 2009