Power conversion circuit and control method thereof

Abstract

A power conversion circuit includes a transformer, a switching transistor, an auxiliary transistor, and a control circuit. The transformer includes a primary coil, a secondary coil, and an auxiliary coil. The primary coil receives an input voltage, and the secondary coil generates an output voltage. The switching transistor is coupled between the primary coil and a ground. The auxiliary coil is coupled between a terminal of the auxiliary coil and the ground. The control circuit drives the switch transistor based on the output voltage. When the transformer ends the demagnetization, the control circuit turns on the auxiliary transistor in a zero-voltage switching period, so that zero-voltage switching is achieved when the switching transistor is turned on once again.

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