Circuits and methods using power supply output voltage to power a primary side auxiliary circuit
AssigneeQueen's University at Kingston
InventorsYang Chen, Yan-Fei Liu
Life of this patent
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Abstract
In an AC-DC converter having a primary side control circuit, auxiliary power for the control circuit is derived from the converter secondary side through an isolated DC-DC converter. The circuits and methods solve the problem of supplying primary side auxiliary power during light load or no load operation of the AC-DC power converter. Since the output voltage of the AC-DC converter is normally regulated at a fixed level, the auxiliary voltage that is generated by the isolated DC converter is regulated. In some cases the isolated DC-DC converter may not need to be regulated, which simplifies the design and reduces overall cost.
Claims22
An AC-DC converter, comprising:
- a primary side including an AC input and a primary side circuit having at least one switch;
- an isolating transformer;
- a secondary side including a secondary side circuit and a DC output;
- a control circuit that provides control signals to the at least one switch of the primary side circuit;
- and
- a DC power circuit having a secondary side that receives DC output power from the secondary side of the AC-DC converter, and a primary side that outputs DC power to the control circuit;
- wherein the DC power circuit secondary side and primary side are isolated.
A method for providing auxiliary power for a primary side control circuit of an AC-DC converter, comprising:
- providing an AC-DC converter primary side including an AC input and a primary side control circuit having at least one switch, and an AC-DC converter secondary side including a secondary side circuit and a DC output;
- implementing a DC power circuit having a secondary side that receives DC output power from the secondary side of the AC-DC converter, and a primary side that outputs DC auxiliary power to the primary side control circuit;
- wherein the DC power circuit secondary side and primary side are isolated.
Dependencies are inferred from the claim text.