Abstract
Using a half-bridge converter and a half-bridge inverter respectively in the AC/DC conversion section of an uninterrruptible power supply (UPS) makes it possibl to omit the isolating transformer and render the UPS both more efficient and smaller. But as using such a circuit necessitates storage batteries of very high voltage, it is in particular not suitable as a type of circuit for small-capacity of the under 3kVA class. We therefore conceived a technique in order to lower necessary storage battery voltage that use a bidirectional chopper. We incorporated this techniques into a 3kVA UPS, allowing us to develop small, high-performance UPS.
