Patent ID: 7558090
Filing Date: 2009-07-07
Classification: H02M

Abstract:
1. A system for transferring an alternating voltage into a direct voltage, comprising: a rectifier connected to a main power supply device to rectify the alternating voltage outputted from the main power supply into a transient direct voltage; a filter connected to the rectifier to filter out a noise from the transient direct voltage for producing a filtered direct voltage; a transformer connected to the filter to transfer the filtered direct voltage into a worked direct voltage; a switch connected to the transformer, the switch has a turn-on status and a cutoff status to control a current which goes through the transformer; a switch control circuit connected to the switch to control the switch be in the turn-on status or the cutoff status; and a voltage feedback circuit connected to the transformer and the switch control circuit, the voltage feedback circuit is used to drive the switch controlling circuit in accordance with the transformer's voltage and reduces a switching loss of the switch wherein the voltage feedback circuit comprises a first diode, a first Zener diode and a second Zener diode, a first capacitance, and a first to a seventh resistance.