From Switching Power Supply Design, 2nd Edition

3.1 Introduction

Half- and full-bridge topologies subject their transistors in the off state to a voltage stress equal to the DC input voltage and not to twice that as do the push-pull, single-ended, and interleaved forward converter topologies. Thus the bridge topologies are used mainly in offline converters where twice the rectified DC would be more than the usual switching transistors could safely tolerate. Bridge topologies hence are almost always used where the nominal AC input voltage is 220 V or higher and frequently for 120 V AC.

An additional valuable feature of the bridge topologies is that primary leakage inductance spikes (Figs. 2.1, 2.10) are easily clamped to the DC supply bus and any energy stored in the leakage inductance is returned to the input bus instead of having to be dissipated in some resistive element.

3.2 Half-Bridge Converter Topology

3.2.1 Basic operation

Half-bridge converter topology is shown in Fig. 3.1. Its major advantage is that, just as the double-ended forward converter, it subjects the off transistor to only V dc and not twice that as do the push-pull and singled forward converter. It is thus widely used in equipment intended for the European market, where the AC input voltage is 220 V.

First consider the input rectifier and filter in Fig. 3.1. It is the universally used scheme when equipment is to be used with minimum changes either on 120-V-AC American or 220-V-AC European power. The circuit always yields roughly 320 V of rectified DC voltage ...

Products & Services
Switching Power Supplies
Switching power supplies are DC sources that use a switching element (normally a power transistor) to generate the desired voltage. Switching power supplies are also called switch-mode products or switching mode power supplies (SMPS).
Switch Mode Transformers
Switch mode transformers (switching transformers) are used mainly in switching power supplies and DC-DC converters. They provide a storage element for transferring energy from input to output in discrete packets as required in switching power supplies, regulators and converters.
Rectifier diodes are designed for use in rectification circuits. Rectifiers are used to convert AC to DC.
Linear Power Supplies
Linear power supplies accept AC inputs and provide one or more DC outputs for a wide variety of computer and industrial applications. They use an active element (normally a power transistor) operating in its linear region to generate a desired voltage.
DC-DC Converter Chips
DC-DC converter chips provide a regulated DC voltage output from a different, unregulated input voltage. 

Topics of Interest

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