Regulated transformer rectifier unit

TLDR: In this paper, a transformer rectifier unit is provided for developing regulated DC output power from first and second sources of unregulated DC power, which includes a transformer having a primary winding connectable to a source of AC input power and first and secondary windings.

Abstract: A transformer rectifier unit is provided for developing regulated DC output power from first and second sources of unregulated DC power. The transformer rectifier unit includes a transformer having a primary winding connectable to a source of AC input power and first and second secondary windings. The first secondary winding develops AC power at a first level and the second secondary winding develops AC power at a second level lower than the first level. First and second rectifier circuits are respectively coupled to the first and second secondary circuits for rectifying the AC power therefrom to DC power having corresponding first and second DC levels. A switch is coupled between an output of the first rectifier circuit and an output of the second rectifier circuit and is operable in first and second switching states to provide DC output power from one of the rectifier circuits to a load. A pulse-width modulation control circuit is responsive to the difference between a desired DC output level and an actual DC output level and operates the switch between first and second states to provide regulated DC output power. In an alternative embodiment of the invention, the transformer comprises Y-Δ secondary winding sets.