Half-Bridge vs Buck Converter
An H-bridge is not a half-bridge. The 'H' in H-bridge is not shorthand for half-bridge. An H-bridge is formed with two half-bridges and to produce a circuit in the shape of an 'H'.
An H-bridge's only job is to allow you to take a single-polarity source and swap it's polarity across a load. That load can be a a motor, an electromagnet, a speaker, a transformer, whatever. It doesn't change the fact it is an H-bridge.
A half-bridge is two switches connected together between a power rail. It's job is to switch the node common to both switches to one rail or the other, or disconnect it from both.
A simple buck converter uses a high-side switch and a free-wheeling diode sharing a common node with the inductor.
You can increase the efficiency of a buck converter by replacing the free-wheeling diode with a low-side switch and controlling it appropriately. This removes the forward voltage drop of the free-wheeling diode. This forms a half-bridge with the high-side switch that was already there. Replacing the free-wheeling diode with a switch is also called &quot;synchronous rectification&quot;.



simulate this circuit &ndash; Schematic created using CircuitLab