Arrangement for supplying direct current to a consumer from an alternating current source with interposed transformer and rectifier establishing periodic rapid changes in transformation ratio

Claim 1

In an arrangement for providing direct current to a coNsumer from a supply source of alternating current which includes a transformer having its primary side connected to said alternating current supply source and its secondary side connected to a rectifier system from which direct current is fed to the consumer through a filter tuned to double the frequency of the alternating current supply source, the improvement wherein the secondary side of said transformer includes at least one winding having at least one tapped junction point intermediate the end junction points thereof, wherein said rectifier system is constituted by a fullwave rectifier bridge for each such tapped secondary winding including non-controllable valves and valves of the controllable semi-conductor type, wherein the number of junction points of each such secondary winding corresponds to the number of bridgearm pairs, wherein each mid-point of a bridge-arm pair is connected to one junction point of the secondary winding, and wherein control means are provided for selectively actuating the controllable semi-conductor valves of each such bridge circuit in functional relation to the alternating current supply source so as to effect a step-like increase in the transformation ratio of said transformer and hence also the voltage applied to said rectifier system by said one or more tapped secondary windings.