Patent ID: 7200015
Filing Date: 2007-04-03
Classification: H02M

Abstract:
1. Apparatus for converting a first DC or AC input voltage to a second DC output voltage, said apparatus comprising: a power transformer having primary and secondary windings, wherein an input alternating current is provided to said primary winding and an output alternating voltage is induced in said secondary winding; a rectifier circuit coupled to said secondary winding for converting said output alternating voltage to DC output voltage pulses; an output filter including output capacitors coupled between said rectifier circuit and output terminals of the apparatus for filtering said DC output voltage pulses prior to providing said DC output voltage pulses via said output terminals to a DC load, wherein said output capacitors are charged to a high voltage by said DC output voltage pulses; a transistor switch and bleed resistor combination connecting said output capacitors to an output return, wherein said transistor switch is non-conductive during normal operation of the apparatus and said transistor switch is rendered conductive for automatically discharging the output capacitors through the bleed resistor to the output return when the apparatus is turned off and the DC load is removed from the apparatus; and a peak detector coupled to the secondary winding of said power transformer and further coupled to said transistor switch via a resistor, wherein said peak detector provides said transistor switch with a peak output voltage pulse from the secondary winding of said power transformer for filtering out peaks of the DC pulses provided to said transistor switch and for maintaining said transistor switch nonconductive during normal operation of the apparatus, and wherein said peak detector compares a maximum value of the output voltage on the secondary winding of said power transformer with a root-mean-square value of said DC output voltage pulses from said output capacitors for providing a sliding threshold level not referenced to a fixed voltage for turning on said transistor switch, and wherein lossy, heat generating components are avoided during operation of the apparatus.