AC/DC switch mode power supply

The power factor correction (PFC) alternating current to direct current (AC/DC) converter comprising:

(a) a power factor correction cell having an AC input, a switch, a DC output and a flyboost transformer having a plurality of windings;

(b) a Direct current to direct current (DC/DC) converter cell having both DC input terminals and DC output terminals; and,

(c) means for operating the power factor correction cell (PFC) as a flyback transformer in a flyback mode and as a boosting device in a boost mode as a function of the magnitude of the input voltage to the power factor correction cell whereby the converter has an improved power factor correction.

The power factor correction AC/DC converter according to claim 1 wherein said power factor correction cell has two discharging paths, a first discharging path to a DC bus storage capacitor and a second discharging path to the output.

The power factor correction AC/DC converter according to claim 1 wherein said power factor correction cell transfers a portion of its power directly to said DC output terminals.

The power factor correction AC/DC converter according to claim 1 wherein said the DC/DC converter cell has means providing for operation at both discontinuous conduction mode (DCM) or continuous conduction mode (CCM) without voltage trouble at a selected load condition.

The typical prior schemes suffer from high direct current (DC) bus voltage stress, low efficiency and/or high output ripple, since all energy is firstly transferred from line source to DC bus storage capacitors by PFC cell, and then transferred to the load by a direct current to direct current (DC/DC) conversion cell.