Patent ID: 8582318

Claim:
A method for potential-isolated power transfer with two output DC voltages by means of a circuit for the potential-isolated power transfer from a primary side to a secondary side with first and second secondary-side output DC voltages, wherein the absolute value of the first output DC voltage is higher than the absolute value of the second output DC voltage, the circuit comprising: a transformer for power transfer, which has on a primary side a first winding and a second winding with a common center tap, and on a secondary side a third winding, the ratio of the number of turns of the first winding to the second winding is a function of the ratio of the first and second secondary-side output DC voltages, the center tap is connected to a DC voltage source, the first winding is connected to a first transistor and the second winding is connected to a second transistor and the first and second transistors are each connected by a second load connection to a primary-side reference potential, wherein the two connections of the secondary-side third winding are respectively connected to the anode of a first diode and a second diode, at the respective cathodes of which the respective output DC voltage is present; wherein the number of turns of the first winding is less than the number of turns of the second winding, and wherein the number of turns of the third winding is equal to the number of turns of the first winding; and the number of turns of the first winding is less than the number of turns of the second winding, and wherein the number of turns of the third winding is an integral multiple or an integral fraction of the number of turns of the first winding wherein the method comprises the step of: switching the transistors for power transfer in a manner offset with respect to one another with a duty ratio that is inversely proportional to the number of turns of the assigned winding of the transformer.