High power factor isolated buck-type power factor correction converter

A power converter comprising:

• a. a first rectifier circuit configured to receive an input AC voltage and to output a full-wave rectified DC voltage;
• b. a single-stage isolated buck-type converter configured to receive the full-wave rectified DC voltage as input, wherein the single-stage isolated buck-type converter includes an isolation transformer comprising a first secondary winding and a second secondary winding;
• c. a second rectifier circuit coupled to the first secondary winding;
• d. a third rectifier circuit coupled to the second secondary winding;
• e. a tap switch coupled to an output of the third rectifier circuit, wherein the tap switch is configured to adjust a functional turns ratio of the isolation transformer;
• and
• f. a bulk capacitor coupled to an output of the second rectifier circuit and the third rectifier circuit, wherein a voltage across the bulk capacitor is a DC voltage output of the power converter.

A power converter comprising:

• a. a first rectifier circuit configured to receive an input AC voltage and to output a full-wave rectified DC voltage;
• b. a first single-stage isolated buck-type converter coupled to the first rectifier including a first isolation transformer having a first primary winding and a first secondary winding, wherein the first primary winding is coupled to the first rectifier circuit and is configured to receive the full-wave rectified DC voltage;
• c. a second single-stage isolated buck-type converter including a second isolation transformer having a second primary winding and a second secondary winding, wherein the second primary winding is coupled to the first rectifier circuit and is configured to receive the full-wave rectified DC voltage, further wherein when the full-wave rectified DC voltage is above a reference level both the first single-stage isolated buck-type converter and the second single-stage isolated buck-type converter are configured to operate, and when the full-wave rectified DC voltage is below the reference level the first single-stage isolated buck-type converter is configured to operate and the second single-stage isolated buck-type converter is shorted to be inoperable;
• d. a second rectifier circuit coupled to the first secondary winding of the first isolation transformer;
• e. a third rectifier circuit coupled to the second secondary winding of the second isolation transformer;
• and
• f. a bulk capacitor coupled to an output of the second rectifier circuit and an output of the third rectifier circuit, wherein a voltage across the bulk capacitor is a DC voltage output of the power converter.