Patent ID: 6744642
Filing Date: 2004-06-01
Classification: H02M,Y02B

Abstract:
A reset circuitry for resetting an internal magnetic field of a transformer in a power converter when a main switch of the power converter is turned off, the reset circuit comprising:a first capacitor connected in series with a winding of the transformer; a rectifier connected in parallel with a series circuit comprising the first capacitor and the winding of the transformer; a second capacitor; an auxiliary switch connected in series with the second capacitor to form a series circuit to be connected in parallel with the rectifier; and a switch control circuit configured to turn on the main switch and turn off the auxiliary switch instantaneously so as to discharge magnetizing energy of a magnetizing inductor of the transformer and store the magnetizing energy in the magnetizing inductor and charge the first capacitor, and turn on the auxiliary switch and turn off the main switch after a short period of time so as to transmit the magnetizing energy and the energy stored in the first capacitor to a second capacitor, and charge the magnetizing inductor and the first capacitor through the second capacitor after the magnetizing energy of the magnetizing inductor is fully discharged.