Patent ID: 7778050
Filing Date: 2010-08-17
Classification: H02M

Abstract:
1. An energy transfer device comprising: a transformer having a primary winding, a secondary winding, and an auxiliary winding; a switching element series-connected to the primary winding; a control circuit that controls a switching operation of the switching element to perform switching control on a first DC voltage to be inputted to the switching element via the primary winding; an output voltage generating unit that converts an AC voltage generated on the secondary winding by the switching control into a second DC voltage and supplies power to a load; and an output voltage detecting circuit that detects a variation in the second DC voltage and transfers a feedback signal for the switching control generated in accordance with the variation to the control circuit, wherein the control circuit includes: a feedback signal control circuit that determines a level of a current flowing through the switching element based on the feedback signal from the output voltage detecting circuit; a switching element current detecting circuit that generates a signal that turns off the switching element when the current flowing through the switching element reaches the level value determined by the feedback signal control circuit; a turn-on detecting circuit that detects, from a voltage of the auxiliary winding, a state of a ringing voltage generated after a secondary current flowing through the secondary winding ceases to flow after the switching element is turned off, and generates a signal for turning on the switching element; and a current peak modulator that performs modulation so that a peak of the current flowing through the switching element periodically and continuously varies within a current range from a first current value to a second current value.