High input voltage DC to DC power converter

Claim 1

Voltage conversion apparatus for converting a first DC voltage of high magnitude between a pair of input power buses to a second DC voltage between a pair of output power buses, said apparatus comprising: a. a plurality of staggered-mode DC to DC converters, each of said converters including first and second independent conversion units sharing a common pair of power output terminals, with each of said units comprising first and second power input terminals, a relatively low voltage power switching device having alternative conducting and non-conducting states, control terminals coupled to said switching device, a power transformer having primary and secondary windings, said primary winding being serially connected with said switching device between said input terminals, and rectifying means for connecting said secondary winding to the pair of power output terminals of the associated converter so that the output current from that converter is unidirectional; b. means for connecting said power input terminals of the first conversion units of all of said plurality of converters in a first series string between the input power buses; c. means for connecting said power input terminals of the second conversion units of all of said plurality of converters in a second series string between the input power buses, said second string being separate from said first string; d. a plurality of equal value voltage dividing capacitors, half of said capacitors being respectively connected across the power input terminals of the conversion units forming said first string and the other half of said capacitors being respectively connected across the power input terminals of the conversion units forming said second string; e. means for connecting the pairs of power output terminals of all of said plurality of converters in parallel to the output power buses, whereby the output buses are supplied with the sum of the output currents from said converters; f. a filter capacitor connected between said output power buses; and g. control means connected to the control terminals of said first and second conversion units of all of said converters for simultaneously applying to the control terminals of said first units a first periodic state-changing signal that causes the respective switching devices of said first units to be in conducting states during predetermined intermittent intervals and for simultaneously applying to the control terminals of said second units a second periodic state-changing signal that causes the respective switching devices of said second units to be in conducting states during intervals that are staggered with respect to said predetermined intermittent intervals.