The full-bridge converter adds two additional transistors
to the half-bridge converter. This means that four transistors are available
to provide power to the output section, so this type of converter is used
in power supplies in excess of 1000 Watts. Fig. 1 shows the schematic
of the full-bridge converter. Each transistor has a clamping diode connected
across its collector-emitter terminals and they are driven alternately
in pairs. Transistors T1 and T3 are energized together for one half-cycle, and transistors T2 and T4 are energized together for the other half-cycle.
One advantage of the full-bridge converter is that it only requires one
capacitor for smoothing the output voltage, whereas the half-bridge converter
required two. The full-bridge converter will be used in larger power supplies
usually over 1000 Watts. Since this type of converter is more complex,
it's normally used in the largest types of power supplies.
Above: Fig. 1: Schematic of a full-bridge converter.