Patent ID: 8772968

Claim:
A circuit for providing a.c. power from a plurality of unregulated voltage sources, each of the unregulated voltage sources having outputs for outputting a temporally variable output d.c. voltage, wherein the circuit comprises: a plurality of regulated voltage sources, switched parallel, each regulated voltage source being configured to receive power from a respective one of the plurality of unregulated voltage sources, each of said plurality of regulated voltage sources including a step-up converter and an associated regulating device; an a.c.-d.c. converter circuit; and a regulating unit; wherein each said step-up converter has a positive input connected to one of the outputs of the respective unregulated voltage source thereby forming a positive branch, a first coil positioned in said positive branch downstream of said positive input, a negative input connected to another of the outputs of the respective unregulated voltage source thereby forming a negative branch, and a second coil positioned in said negative branch downstream of said negative input, and a semi-bridge circuit connecting said first and second coils, said semi-bridge circuit including at least first and second power transistors having a first center tap therebetween, at least first and second capacitors connected in series having a second center tap therebetween, said second center tap being connected to said first center tap, a first diode in said positive branch downstream of said first coil, said first diode having an anode connected to said first power transistor and a cathode connected to said first capacitor, said cathode thereof also forming a first output of said regulated voltage source, and a second diode in said negative branch downstream of said second coil, said second diode having a cathode connected to said second power transistor and an anode connected to said second capacitor, said cathode thereof also forming a second output of said regulated voltage source, wherein said regulating unit includes a measuring device for measuring an intermediate circuit voltage of said a.c.-d.c. converter circuit and is connected with said regulating devices for controlling the regulated voltage sources.