An H-bridge module is equipped with four IGBTs and four free-wheeling diodes, which usually have 600 V, 1200 V or 1700 V blocking voltage. The IGBTs and diodes often share the same current rating. MOSFETs with 600 V are also frequently used in H-bridges as SiC components are used more and more. Nearly all modules are equipped with an NTC or PTC alongside the power semiconductors.
H-bridge modules are often used in solar inverters, UPS systems, welding equipment and power supplies.
How it works
In single-phase photovoltaic inverters and single-phase UPS applications, H-bridges serve to convert AC into DC voltage.
The load voltage's polarity alternates periodically, so the full DC-link voltage can be used, rather just half as is the case with a single half-bridge. This is why most single-phase applications operate with a DC-link voltage of around 400 V.
H-bridges are also used in welding devices and in other power supplies. In these applications, they drive a transformer that usually reduces the DC-link voltage to a lower potential.
This is generally done at high switching frequencies ranging up to and beyond 100 kHz to enable the use of small inductors.
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