Single-stage single switch power factor correction circuit having isolated output and boost inductor between AC source and bridge rectifier

摘要

A flyback converter utilizes a boost inductor (L4) coupled between a source of AC power and a bridge rectifier (4) to provide power factor correction. A primary winding (P1) of the flyback transformer (T1) is coupled in series with a storage capacitor (C3) across the output of the bridge rectifier (4). A circuit, which includes a switching transistor (Q1), is also coupled across the output of the bridge rectifier (4) to provide a low resistance path when the switch is closed. The cores of the boost inductor (L4) and the transformer (T1) are loaded with energy when the switch (Q1) is closed. When the switch (Q1) opens, the energy stored in the magnetic cores is transferred to the output via the transformer secondary winding (S1) and rectification circuitry (CRrec).