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U.S. Department of Energy
Office of Scientific and Technical Information

Free-running flyback dc power supply

Patent ·
OSTI ID:5199857

A free-running flyback dc power supply includes a transformer having at least one primary and one secondary winding, a transistor switch in series with the primary winding for controlling when current from a source of dc power is coupled through said winding, and a rectifier circuit attached to the secondary winding for generating a dc output voltage. A conventional regulator circuit causes the transistor switch to turn off primary winding current as a function of the present value of dc output voltage. A second circuit senses excessive current in the primary winding and causes the transistor switch to turn off independently of said regulator circuit, to protect against damage to the transistor switch or transformer. A third circuit detects when the dc source voltage is below a predetermined minimum and causes the transistor switch to turn off independently of said regulator circuit. Regulation of the output dc voltage is also maintained as a function of the present value of dc source voltage. An additional circuit causes the regulator circuit to turn off the transistor switch early if the dc output voltage drops below a predetermined minimum.

Assignee:
Astec Components Ltd
Patent Number(s):
US 4323961
OSTI ID:
5199857
Country of Publication:
United States
Language:
English