Single stage high power-factor converter

• US 6,307,761 B1
• Filed: 11/17/1999
• Issued: 10/23/2001
• Est. Priority Date: 03/23/1998
• Status: Expired due to Fees

• Current Assignee: Fidelix Y.K.
• Original Assignee: Fidelix Y.K.
• Inventors: Nakagawa, Shin
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US09/424,020
• Time in Patent Office: 706 Days
• Field of Search: 363/65, 363/67, 363/69, 363/70
• US Class Current: 363/65
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• CPC Class Codes: H02M 3/285 Single converters with a plurality of output stages connected in parallel parallel operation of a plurality of converters in dc distribution networks H02J1/10
• CPC Class Codes: H05B 41/2821 by means of a single-switch converter or a parallel push-pull converter in the final stage H05B41/285 takes precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

An output of a first converter for switching a rectified line current and an output of a second converter for switching a direct current are added together so that an efficiency, a power factor, a holding time, and a ripple characteristic can be improved. Further, the power supply apparatus can be made compact and the cost for manufacturing the apparatus can be reduced. A flyback converter type output circuit and a forward converter type output circuit are used in a parallel manner so that a transformer having a high efficiency can be used, and it becomes easier to control the apparatus.

Claims

1. An AC-DC converter for converting single phase AC from a source of single phase AC power to DC, the converter comprising:

an input for connection to a source of single phase AC and an output for connection to a load;

a first circuit for converting single phase AC into DC, the first circuit including a first transformer with primary and secondary windings, a first rectifier coupled to said input and to a primary winding of the transformer for supplying rectified AC to the primary winding, and a second rectifier coupled to a secondary winding of the transformer for providing a rectified current;

a second circuit for converting single phase AC into a smoothed DC, the second circuit including a second transformer with a primary winding coupled to said input and a secondary winding, a capacitor intermediate said input and the primary winding of the second transformer for smoothing the current and a third rectifier coupled to a secondary winding of the second transformer for providing a rectified current;

a combining circuit coupled to the second rectifier and to the third rectifier and to said output to provide a combined current which is a combination of the second rectifier current and the third rectifier current;

switching means coupled to the primary windings of the first and second transformers for providing a current at the secondary winding of the first transformer which has a predetermined wave shape and for providing a current at the secondary winding of the second transformer which has a wave shape different from said predetermined wave shape; and

control means coupled to at least said output and to said switching means to provide second and third rectifier currents which, when combined, provide a combined current which is DC of a substantially constant value with a predetermined load coupled to said output.

2. An AC-DC converter according to claim 1 wherein the primary winding of the second transformer is coupled to the input by a fourth rectifier.

3. An AC-DC converter according to claim 2 wherein the switching means comprises a switch coupled to both the primary winding of the first transformer and the primary winding of the second transformer.

4. An AC-DC converter according to claim 2 wherein the switching means comprises a first switch coupled to the primary winding of the first transformer and a second switch coupled to the primary winding of the second transformer.

5. An AC-DC converter according to claim 1 wherein the switching means comprises a first switch coupled to the primary winding of the first transformer and a second switch coupled to the primary winding of the second transformer.

6. An AC-DC converter for converting single phase AC from a source of single phase AC power to DC, the converter comprising:

an input for connection to a source of single phase AC and an output for connection to a load;

a first circuit for converting single phase AC into DC, the first circuit including a first transformer with primary and secondary windings, a first rectifier coupled to said input and to a primary winding of the transformer for supplying rectified AC to the primary winding, and a second rectifier coupled to a secondary winding of the transformer for providing a rectified current;

a second circuit for converting single phase AC into a smoothed DC, the second circuit including a second transformer with primary and secondary windings, a third rectifier coupling a primary winding of the second transformer to said input, a capacitor intermediate said third rectifier and the primary winding of the second transformer for smoothing the current and a fourth rectifier coupled to a secondary winding of the second transformer for providing a rectified current;

a combining circuit coupled to the second rectifier and to the fourth rectifier and to said output to provide a combined current which is a combination of the second rectifier current and the fourth rectifier current;

a first switch in series with the primary winding of the first transformer for providing a current at the secondary winding of the first transformer which has a predetermined wave shape and a second switch means in series with the primary winding of the second transformer for providing a current at the secondary winding of the second transformer which has a wave shape different from said predetermined wave shape; and

control means coupled to said output and to said first switch and said second switch to provide second and fourth rectifier currents which, when combined, provide a combined current which is DC of a substantially constant value with a predetermined load coupled to said output.

7. An AC-DC converter according to claim 6 wherein the combining circuit comprises a capacitor electrically in parallel with the output and the second and fourth rectifiers are connected electrically in parallel with the capacitor.

8. An AC-DC converter for converting single phase AC from a source of single phase AC power to DC, the converter comprising:

an input for connection to a source of single phase AC and an output for connection to a load;

a first circuit for converting single phase AC into DC, the first circuit including a first transformer with at least two primary windings and a secondary winding, a first rectifier coupled to said input and to one of the primary windings of the transformer for supplying rectified AC to the primary winding, and a second rectifier coupled to a secondary winding of the transformer for providing a rectified current;

a second circuit for converting single phase AC into a smoothed DC, the second circuit including a second transformer with primary winding coupled to said input and a secondary winding, a capacitor intermediate said input and the primary winding of the second transformer for smoothing the current and a third rectifier coupled to a secondary winding of the second transformer for providing a rectified current;

the other of the primary windings of the first transformer being coupled to the primary winding of the second transformer;

a combining circuit coupled to the second rectifier and to the third rectifier and to said output to provide a combined current which is a combination of the second rectifier current and the third rectifier current;

switching means electrically in series with said one of the primary windings of the first transformer and electrically in series with the primary winding of the second transformer for providing a current at the secondary winding of the first transformer which has a predetermined wave shape and for providing a current at the secondary winding of the second transformer which has a wave shape different from said predetermined wave shape; and

control means coupled to said output, to said first transformer and to said switching means to provide second and third rectifier currents which, when combined, provide a combined current which is DC of a substantially constant value with a predetermined load coupled to said output.

9. An AC-DC converter according to claim 8 wherein the primary winding of the second transformer is coupled to the input by a fourth rectifier.

10. An AC-DC converter according to claim 9 wherein the switching means comprises a switch electrically in series with said one of the primary windings of the first transformer and electrically in series with the primary winding of the second transformer.

11. An AC-DC converter for converting single phase AC from a source of single phase AC power to DC, the converter comprising:

an input for connection to a source of single phase AC and an output for connection to a load;

a first circuit for converting single phase AC into DC, the first circuit including a first transformer with primary and secondary windings, a first rectifier coupled to said input and to a primary winding of the transformer for supplying rectified AC to the primary winding, and a second rectifier coupled to a secondary winding of the transformer for providing a rectified current;

a second circuit for converting single phase AC into a smoothed DC, the second circuit including a second transformer with a primary winding coupled to said input and a secondary winding, a capacitor intermediate said input and the primary winding of the second transformer for smoothing the current and a third rectifier coupled to a secondary winding of the second transformer for providing a rectified circuit;

the primary winding of the first transformer being coupled to the primary winding of the second transformer;

a combining circuit coupled to the second rectifier and to the third rectifier and to said output to provide a combined current which is a combination of the second rectifier current and the third rectifier current;

a first switch electrically in series with the primary winding of the first transformer and a second switch electrically in series with the primary winding of the second transformer for respectively providing a current at the secondary winding of the first transformer which has a predetermined wave shape and for providing a current at the secondary winding of the second transformer which has a wave shape different from said predetermined wave shape; and

control means coupled to at least said output and to each of said first switch and said second switch to provide second and third rectifier currents which, when combined, provide a combined current which is DC of a substantially constant value with a predetermined load coupled to said output.

12. An AC-DC converter according to claim 11 wherein the primary winding of the second transformer is coupled to the input by a fourth rectifier.

13. An AC-DC converter according to claim 11 wherein the first transformer has a further primary winding coupled to the control means and to the primary winding of the second transformer and wherein the control means is also coupled to the further primary winding of the first transformer.