Fully clamped coupled inductors in power conversion circuits

• US 7,606,051 B1
• Filed: 11/02/2006
• Issued: 10/20/2009
• Est. Priority Date: 11/03/2005
• Status: Expired due to Fees

• Current Assignee: Ernest Henry Jr. Wittenbreder
• Original Assignee: Ernest Henry Jr. Wittenbreder
• Inventors: Wittenbreder, Ernest Henry Jr.
• Primary Examiner(s): Laxton; Gary L
• Application Number:
  US11/555,759
• Time in Patent Office: 1,083 Days
• Field of Search: 363/16, 363/20, 363/21.01, 363/21.04, 363/21.1, 363/21.12, 363/21.18, 363/56.09, 363/56.11, 363/97, 363/131, 363/39, 363/40
• US Class Current: 363/39
• CPC Class Codes: H02M 1/342 Active non-dissipative snubbers
• CPC Class Codes: H02M 3/33576 having at least one active switching element at the secondary side of an isolation transformer
• 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

Abstract

The subject invention reveals improvement methods for circuits that use a coupled inductor wherein overshoot and ringing associated with leakage inductance of said coupled inductor is entirely eliminated by addition of non-dissipative active clamp networks that clamp each winding during each operating state of a power supply containing said coupled inductor. A further improvement applicable to zero voltage switching circuits that employ an inductor for driving a zero voltage turn on switching transition of a switch enables elimination of said inductor and preserves said zero voltage switching properties by adding leakage inductance to a coupled inductor without any adverse overshoot and ringing effects associated with said leakage inductance. The subject invention also reveals a coupled inductor with enhanced leakage inductance which can be used with said other improvements. Example circuits including zero voltage switching flyback and forward converters which require only one magnetic circuit element are revealed. Zero voltage switching tapped inductor buck and boost converters with a single magnetic circuit element are also revealed.

Claims

1. A fully clamped coupled inductor power conversion circuit formed by applying an improvement method to a unclamped coupled inductor power conversion circuit, wherein said unclamped coupled inductor power conversion circuit has at least two operating states, and wherein said unclamped coupled inductor power conversion circuit comprises at least a first coupled inductor having at least a first winding and a second winding, an inductance connected in series with said first coupled inductor, and a first switch means, wherein at least one of said windings of said first coupled inductor is unclamped in at least one of said operating states of said unclamped coupled inductor power conversion circuit, said improvement method comprising the following steps,

Step (1):

adding an active clamp network such that said active clamp network is coupled to said unclamped winding of said first coupled inductor, said active clamp network comprising,

second switch means, wherein said second switch means are placed in a conducting state during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped winding of said first coupled inductor was unclamped and wherein said second switch means are placed in a non-conducting state during all other operating states, and

a capacitor coupled to said unclamped winding of said first coupled inductor through said second switch means during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped winding of said first coupled inductor was unclamped,

Step (2);

repeating step (1) for each of said windings and each of said operating states of said unclamped coupled inductor power conversion circuit until all of said windings of said coupled inductor are clamped during all of said operating states,

whereby said fully clamped coupled inductor power conversion circuit becomes fully clamped by application of said improvement method to said unclamped coupled inductor power conversion circuit thereby eliminating ringing and over shoot associated with said inductance.

2. The fully clamped coupled inductor power conversion circuit as set forth in claim 1, wherein said switch means comprise semiconductor switch means.

3. The fully clamped coupled inductor power conversion circuit as set forth in claim 2, wherein said semiconductor switch means comprise transistors.

4. The fully clamped coupled inductor power conversion circuit as set forth in claim 3, wherein said transistors comprise mosfets.

5. The fully clamped coupled inductor power conversion circuit as set forth in claim 1, wherein said inductance comprises a leakage inductance inherent to said first coupled inductor.

6. The fully clamped coupled inductor power conversion circuit as set forth in claim 1, wherein said inductance comprises a discrete inductor structurally separated from said first coupled inductor.

7. The fully clamped coupled inductor power conversion circuit as set forth in claim 1, wherein said first switch means is a main switch means and said inductance contributes energy to reduce an output voltage and turn on switching power losses of said first switch means during a turn on switching transition of said first switch means.

8. The fully clamped coupled inductor power conversion circuit as set forth in claim 1 formed by adding two of said active clamp networks wherein the dc terminal voltages of said capacitors of said active clamp networks are substantially identical.

9. The fully clamped coupled inductor power conversion circuit as set forth in claim 8, wherein said capacitors of said active clamp networks are combined in a single common capacitor.

10. The fully clamped coupled inductor power conversion circuit as set forth in claim 1, further comprising additional windings coupled to said first coupled inductor, wherein said improvement method is applied to all of said additional windings during all of said operational states such that all of said windings of said first coupled inductor are clamped during all of said operating states.

11. A fully clamped coupled inductor power conversion circuit formed by applying an improvement method to a unclamped coupled inductor power conversion circuit, wherein said unclamped coupled inductor power conversion circuit has at least two operating states, and wherein said unclamped coupled inductor power conversion circuit comprises at least a first coupled inductor having at least a first winding and a second winding, a first inductance connected in series with said first coupled inductor, a second coupled inductor having at least a first winding and a second winding, wherein said first winding of said first coupled inductor and said first winding of said second coupled inductor are connected in a series combination, a second inductance connected in series with said second coupled inductor, and first switch means, wherein said series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor is unclamped in one of said operating states of said unclamped coupled inductor power conversion circuit, said improvement method comprising the following steps,

Step (1):

adding an active clamp network such that said active clamp network is coupled to said unclamped series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor, said active clamp network comprising,

second switch means, wherein said second switch means are placed in a conducting state during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor was unclamped and wherein said second switch means are placed in a non-conducting state during all other operating states, and

a capacitor coupled to said unclamped series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor through said second switch means during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor was unclamped,

Step (2);

repeating step (1) for each of said operating states of said unclamped coupled inductor power conversion circuit until said series combination of said first winding of said first coupled inductor and said first winding of said second coupled inductor is clamped during all of said operating states,

Step (3);

adding an active clamp network such that said active clamp network is coupled to an unclamped second winding of said first coupled inductor, if there exists an unclamped second winding of said first coupled inductor, or coupled to an unclamped second winding of said second coupled inductor, if there exists an unclamped second winding of said second coupled inductor, said active clamp network comprising,

third switch means, wherein said third switch means are placed in a conducting state during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped second winding was unclamped and wherein said third switch means are placed in a non-conducting state during all other operating states, and

a capacitor coupled to said unclamped second winding through said third switch means during said operating state of said unclamped coupled inductor power conversion circuit in which said unclamped second winding was unclamped,

Step (4);

repeating step (3) for each of said second windings and each of said operating states of said unclamped coupled inductor power conversion circuit until all of said second windings are clamped during all of said operating states,

whereby said fully clamped coupled inductor power conversion circuit becomes fully clamped by application of said improvement method to said unclamped coupled inductor power conversion circuit thereby eliminating ringing and over shoot associated with said inductances.

12. The fully clamped coupled inductor power conversion circuit as set forth in claim 11, further comprising additional windings coupled to said first coupled inductor, wherein said improvement method is applied to all of said additional windings during all of said operational states such that all of said windings of said first coupled inductor are clamped during all of said operating states.

13. The fully clamped coupled inductor power conversion circuit as set forth in claim 11, further comprising additional windings coupled to said second coupled inductor, wherein said improvement method is applied to all of said additional windings during all of said operational states such that all of said windings of said second coupled inductor are clamped during all of said operating states.

14. The fully clamped coupled inductor power conversion circuit as set forth in claim 11, further comprising additional windings coupled to said first and second coupled inductors, wherein said improvement method is applied to all of said additional windings during all of said operational states such that all of said windings of said first and second coupled inductors are clamped during all of said operating states.

15. The fully clamped coupled inductor power conversion circuit as set forth in claim 11, wherein said switch means comprise semiconductor switch means.

16. The fully clamped coupled inductor power conversion circuit as set forth in claim 15, wherein said semiconductor switch means comprise transistors.

17. The fully clamped coupled inductor power conversion circuit as set forth in claim 16, wherein said transistors comprise mosfets.

18. The fully clamped coupled inductor power conversion circuit as set forth in claim 11, wherein said first switch means is a main switch means and said inductances contribute energy to reduce an output voltage and turn on switching power losses of said first switch means during a turn on switching transition of said first switch means.

19. The fully clamped coupled inductor power conversion circuit as set forth in claim 11, wherein said inductances comprise leakage inductances inherent to said coupled inductors.

20. The fully clamped coupled inductor power conversion circuit as set forth in claim 11, wherein said inductances comprises discrete inductors structurally separated from said coupled inductors.