Power converter having regulated dual outputs

• US 6,501,193 B1
• Filed: 09/07/2001
• Issued: 12/31/2002
• Est. Priority Date: 09/07/2001
• Status: Expired due to Term

• Current Assignee: Bel Power Solutions Inc.
• Original Assignee: Power-One Incorporated (ABB Limited)
• Inventors: Krugly, Simon
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/948,456
• Time in Patent Office: 480 Days
• Field of Search: 307/31, 307/32, 307/33, 307/34, 307/35, 363/21.04, 363/21.09
• US Class Current: 307/31
• CPC Class Codes: H02M 3/33561 having more than one ouput with independent control

Abstract

A power converter provides regulated dual outputs. The power converter includes a transformer having a primary winding, and first and second secondary windings. On a primary side of the converter, there is provided the primary winding of the transformer, and a first switch having an activation terminal, where the switch is coupled to the primary winding. A first controller has its input connected to the first output terminal of the converter and its output connected to the activation terminal of the switch. On a secondary side of the converter, there is provided first and second secondary sections. The first section includes the first secondary winding and a first inductor coupled between the first secondary winding and the first output terminal. The second section includes the second secondary winding and a second inductor coupled between the second secondary winding and the second output terminal. The first and second inductors may be magnetically coupled or independent. The second secondary section also includes a second switch adapted to apply a regulating voltage to the second inductor during a regulating period of the converter. The regulating voltage increases the volt-seconds applied to the second inductor to regulate the voltage at the second output terminal.

Claims

1. A converter having first and second outputs, comprising:

a transformer having a primary winding and at least one secondary winding;

a primary side including said primary winding of said transformer, a first switch coupled between said primary winding and ground, said first switch adapted to alternatingly apply an input voltage to said primary winding to define successive on-states and off-states of said converter responsive to feedback voltage from said first output;

a secondary side having first and second sections, said first section including said at least one secondary winding and a first inductor coupled between said at least one secondary winding and said first output, said second section including said at least one secondary winding and a second inductor coupled between said at least one secondary winding and said second output; and

a second switch adapted to apply a regulating voltage between said second inductor and said at least one secondary winding during a regulating period corresponding to a portion of said off-states to thereby increase volt-seconds applied to said second inductor.

2. The converter of claim 1, wherein said first and second inductors are inductively coupled together.

3. The converter of claim 1, wherein said first and second inductors are independent from each other.

4. The converter of claim 1, further comprising an auxiliary voltage source providing said regulating voltage.

5. The converter of claim 1, wherein said first output provides said regulating voltage.

6. The converter of claim 1, wherein said second output provides said regulating voltage.

7. The converter of claim 1, wherein said first section further comprises a first forward rectifier connected in series between said at least one secondary winding and said first inductor, and a first freewheeling rectifier connected in parallel with said at least one secondary winding.

8. The converter of claim 7, wherein said second section further comprises a second forward rectifier connected in series between said at least one secondary winding and said second inductor, and a second freewheeling rectifier connected in parallel with said at least one secondary winding.

9. The converter of claim 8, wherein said first and second forward rectifiers and said first and second freewheeling rectifiers further comprise MOSFETs.

10. The converter of claim 8, wherein said first and second forward rectifiers and said first and second freewheeling rectifiers further comprise diodes.

11. The converter of claim 1, wherein said second switch includes first and second MOSFETs having a series connection and internal body diodes opposing each other.

12. The converter of claim 1, wherein said at least one secondary winding further comprises a first secondary winding and a second secondary winding, said first section further including said first secondary winding and said first inductor coupled between said first secondary winding and said first output, said second section including said second secondary winding and said second inductor coupled between said second secondary winding and said second output.

13. The converter of claim 12, wherein said first secondary winding has N1 turns, said second secondary winding has N2 turns, said first coupled inductor has NL1 turns, and said second coupled inductor has NL2 turns, such that a turns ratio N2/N1 is equal to a turns ratio NL2/NL1.

14. A method of regulating a converter comprising a transformer having a primary winding and at least one secondary winding, comprising the steps of:

alternating between successive on-states and off-states of said converter wherein an input voltage is applied to said primary winding only during said on-states;

rectifying a voltage on said at least one secondary winding to provide said first and second output voltages through respective first and second inductors; and

applying a regulating voltage to one of said first and second inductors during a portion of said off-state of said conductor to thereby increase volt-seconds applied thereto.

15. The method of claim 14, wherein said applying step further comprises applying an auxiliary voltage as said regulating voltage to said one of said first and second inductors.

16. The method of claim 14, wherein said applying step further comprises applying said first output voltage as said regulating voltage to said one of said first and second inductors.

17. The method of claim 14, wherein said applying step further comprises applying said second output voltage as said regulating voltage to said one of said first and second inductors.

18. The method of claim 14, further including the step of inductively coupling said first and second inductors together.

19. The method of claim 14, wherein said at least one secondary winding further comprises a first secondary winding and a second secondary winding, and wherein said rectifying step further comprises rectifying a voltage on said first secondary winding to provide said first output voltages through said first inductor, and rectifying a voltage on said second secondary winding to provide said second output voltage through said second inductor.

20. The method of claim 19, further including the step of selecting a turns ratio of N2/N1 for said transformer wherein said first secondary winding has N1 turns, said second secondary winding has N2 turns, said first inductor has NL1 turns, and said second inductor has NL2 turns, wherein said ratio N2/N1 is equal to a ratio NL2/NL1.