Buck Flyback Converter

Abstract

A two-transistor flyback converter includes a transformer having a primary side and a secondary side, a first transistor connected between an input voltage source and a first terminal of the primary side, a second transistor connected between ground and a second terminal of the primary side, and a diode directly connected between the first terminal of the primary side and ground. The first and second transistors are operable to switch on and off simultaneously and with no current return from the primary side to the input voltage source when the input voltage source is less than a reflected voltage from the secondary side.

Description

technical field [0001] The present application relates to flyback converters, and more particularly to two-transistor flyback converters. Background technique [0002] Flyback converters are used in both AC / DC and DC / DC conversion with galvanic isolation between input and output. A flyback converter is a buck-boost converter in which the inductor is divided to form a transformer, so that the voltage ratio is doubled with the added benefit of isolation. A switch is used to enable the transfer of energy from the input voltage source to the transformer. When the switch is closed, the primary side of the transformer is directly connected to the input voltage source. The primary side current and flux in the transformer increases, thereby storing energy in the transformer. The corresponding voltage induced in the secondary side is negative, thus reverse biasing the diode connecting the secondary side to the load. The output capacitor supplies energy to the output load. When t...

AI Technical Summary

Problems solved by technology

When this topology is used as a power factor correction unit, the input voltage changes from zero to a certain voltage and the power loss caused by the capacitors of the RCD network becomes considerable

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