Electric power conversion systems – Current conversion – Including d.c.-a.c.-d.c. converter
Patent
1989-12-07
1991-04-30
Stephan, Steven L.
Electric power conversion systems
Current conversion
Including d.c.-a.c.-d.c. converter
363 19, 323902, H02M 3338
Patent
active
050123998
ABSTRACT:
A self-oscillation type converter comprises a transformer and a switching transistor. The switching transistor is connected in series to a primary winding of the transformer. A start current is applied from a power supply line to the switching transistor through a start resistor, so that the switching transistor is rendered conductive. A positive feedback is performed through an application of a constant current from a constant current circuit to a base of the switching transistor in response to a voltage generated from a feedback winding, whereby the switching transistor is turned on rapidly. A CR time constant circuit is connected to an output of the constant current circuit. An output of the CR time constant circuit is applied to the base of the transistor, a transistor Q2 is turned on after a lapse of time determined by a time constant of the time constant circuit, so that the switching transistor is forcibly turned off. A voltage outputted to a secondary winding is detected by a voltage comparing circuit. If the outputted voltage becomes higher than a reference voltage, a resistance value of the CR time constant circuit is decreased by a photocoupler, maintaining a turning-on time period of the switching transistor to be constant.
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Okamoto Yasuji
Takemura Hiroshi
Murata Manufacturing Co. Ltd.
Stephan Steven L.
Voeltz Emanuel T.
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