High efficiency PFC power converter

Patent metadata

Field	Value
Publication number	US-9601990-B2
Application number	US-201414446115-A
Country	US
Kind code	B2
Filing date	Jul 29, 2014
Priority date	Oct 28, 2013
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

A power factor correction (PFC) power converter is disclosed that converts AC input power to DC output power. A single stage of the PFC power converter performs both the DC-DC power conversion and the power factor correction for the power converter. The disclosed PFC power converters are efficient in energy conversion and have a power factor of 0.9-1.0. Further, the disclosed PFC power converters can be implemented in both low and high power applications above 75 W.

First claim

The invention claimed is:

1. A power factor correction (PFC) power converter having a power factor, comprising:
an input alternating current (AC) voltage supply configured to supply an input AC voltage that generates an input AC current having an input AC waveform;
an input bridge rectifier stage configured to receive the input AC voltage and to produce a rectified input AC bridge stage voltage that generates a rectified AC bridge stage current having a rectified input AC bridge stage waveform; and
a switching bridge stage having a control circuit that is configured to:
sense the rectified AC bridge stage current;
cause the rectified input AC bridge stage waveform to follow the input AC waveform;
convert the rectified AC bridge stage voltage to a rectified direct current (DC) bridge stage voltage; and
cause the power factor of the PFC power converter to be greater than 0.9.

2. The PFC power converter of claim 1 , wherein the switching bridge stage is a half bridge circuit.

3. The PFC power converter of claim 1 , wherein the switching bridge stage is a full bridge circuit.

4. The PFC power converter of claim 1 , wherein the switching bridge stage operates in an LLC control mode, and wherein the switching bridge stage includes a first primary switch and a second primary switch each having a switching frequency.

5. The PFC power converter of claim 4 , wherein in the LLC control mode, the first primary switch and the second primary switch are operating in zero voltage soft-switching mode.

6. The PFC power converter of claim 4 , wherein the switching bridge stage control circuit causes the rectified input AC bridge stage waveform to follow the input AC waveform by adjusting the amplitude of a voltage gain of the switching bridge stage.

7. The PFC power converter of claim 6 , wherein adjusting the voltage gain of the switching bridge stage is controlled by varying the switching frequency of the first primary switch and the second primary switch.

8. The PFC power converter of claim 6 , further comprising:
a transformer having a primary side and a secondary side related to each other by a transformer turns ratio, the transformer including:
a primary winding, wherein the first primary switch and the second primary switch are electrically coupled to the primary winding on the primary side of the transformer; and
a secondary winding;

a first secondary switch and a second secondary switch electrically coupled to the secondary winding on the secondary side of the transformer, the first secondary switch and the second secondary switch configured to turn on when either the first primary switch is on or the second primary switch is on and cause an active voltage in the secondary winding when the rectified input AC bridge stage waveform is in a valley region.

9. The PFC power converter of claim 8 , wherein the active voltage establishes a reflected current based on a leakage inductance of the secondary winding, the reflected current is reflected to the primary side based on the turns ratio of the transformer.

10. The PFC power converter of claim 9 , wherein a sense resistor electrically coupled to the switching bridge stage senses the reflected current on the primary side of the transformer.

11. The PFC power converter of claim 10 , wherein when the sensed reflected current has a magnitude that is equal to a magnitude of the input AC current, the first secondary switch or the second secondary switch, whichever is active, is turned off, and energy stored in the leakage inductance is delivered to an output of the PFC power converter.

12. The PFC power converter of claim 4 , further comprising:
a transformer having:
a primary winding having a primary side and a secondary side related to each other by a transformer turns ratio, the first primary switch and the second primary switch are electrically coupled to the primary winding;
a secondary winding;
a first output electrically coupled to the secondary winding and having a first output voltage with a first output voltage waveform, the first output regulated by an output regulation circuit configured to cause the first output voltage waveform to follow the input AC waveform of the input AC current;

and
a second output electrically coupled to the secondary winding and having a second output voltage with a second output voltage waveform;

a boost switch having a boost switch operating waveform and electrically coupled to the secondary winding and the second output, the output regulation circuit configured regulate the second output voltage by causing boost energy generated by boost current that builds in the leakage inductance of the secondary winding when the boost switch is turned on to drive the second output voltage when the boost switch is turned off, the boost energy generated by either the first primary switch or the second primary switch being turned on.

13. The PFC power converter of claim 1 , further comprising a transformer having:
a primary winding,
a secondary winding, and
a boost winding having a boost winding voltage;
a boost capacitor electrically coupled to an output of the input bridge stage and an input of the switching bridge stage; and
a rectifier configured to rectify the boost winding voltage and charge the boost capacitor to a boost capacitor voltage.

14. The PFC power converter of claim 13 , wherein the boost capacitor is electrically coupled between power ground and the output of the input bridge stage.

15. The PFC power converter of claim 13 , wherein the rectifier is a full wave rectifier.

Assignees

• Microsemi Corp

Inventors

• Jin Xiao Ping

Classifications

• H02M3/33523

  with galvanic isolation between input and output of both the power stage and the feedback loop · CPC title

• H02M2001/0064

  Electricity · mapped topic

• H02M3/33569

  having several active switching elements (H02M3/3353 takes precedence) · CPC title

• H02M3/33592

  having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer · CPC title

• Y02B70/126

  Cross-Sectional Technologies · mapped topic