A 1 kW unity-power-factor rectifier with isolation and fault protection

A buck-type unity-power-factor rectifier having transformer isolation and short-circuit protection using a single gated switch is configured and experimentally tested as a 1 kW 48 V battery charger, operating from the 120 V line. Analytical results for worst-case fault current are verified, and a novel ripple feedback is shown to improve the short-circuit transient behavior. The buck rectifier demonstrated combines the advantage of normal operation down to zero output voltage with fast transient response due to its low internally stored energy. The AC-line current waveform is good, comparing favorably with conventional approaches. This rectifier appears particularly suitable for applications such as DC-motor drives, battery chargers, and electroplating and arc welding supplies