Power Converter for Led Large Area Light Source Lamp
First Claim
1. Power converter for receiving an input current at an input voltage and for providing an output current at an output voltage, said power converter comprising:
- a transformer having a primary and at least one secondary side, the transformer showing a mutual inductivity Lm and a leakage inductivity Ls;
at least one switching device being operated at an operating frequency ƒ
op at the primary side of said transformer;
a capacitor Cs at the primary side of said transformer, said capacitor forming a resonant circuit with said leakage inductivity Ls of said transformer,wherein said operating frequency, said capacitor Cs, said mutual inductivity Lm and said leakage inductivity Ls are matched such that the effective value of the output current is substantially constant with respect to variations of a load being traversed by said output current.
3 Assignments
0 Petitions
Accused Products
Abstract
Power converter for receiving an input current at an input voltage and for providing an output current at an output voltage. The power converter comprises a transformer (133) having a primary (136) and at least one secondary (138) side, wherein the transformer shows a mutual inductivity Ls. The power converter further comprises at least one switching device (124a, 124b) being operated at an operating frequency ƒop at the primary side of said transformer, and a capacitor Cs at the primary side of the transformer. The capacitor forms a resonant circuit with the leakage inductivity Ls of said transformer, wherein said operating frequency, said capacitor Cs, said mutual inductivity Lm and said leakage inductivity Ls are matched such that the effective value of the output current is substantially constant with respect to variations of a load being traversed by said output current by using resonance principles and operating the power converter in a current source mode.
44 Citations
35 Claims
-
1. Power converter for receiving an input current at an input voltage and for providing an output current at an output voltage, said power converter comprising:
-
a transformer having a primary and at least one secondary side, the transformer showing a mutual inductivity Lm and a leakage inductivity Ls; at least one switching device being operated at an operating frequency ƒ
op at the primary side of said transformer;a capacitor Cs at the primary side of said transformer, said capacitor forming a resonant circuit with said leakage inductivity Ls of said transformer, wherein said operating frequency, said capacitor Cs, said mutual inductivity Lm and said leakage inductivity Ls are matched such that the effective value of the output current is substantially constant with respect to variations of a load being traversed by said output current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
-
-
3. Power converter according to claim 1, wherein said operating frequency ƒ
- op, said capacitor Cs, and said leakage inductivity Ls are matched according to an upper bound for said operating frequency at which an output impedance of said resonant circuit is substantially matched to said load.
-
4. Power converter according to claim 1, wherein said operating frequency ƒ
-
op, said capacitor Cs, and said leakage inductivity Ls are matched according to an upper bound for said operating frequency, such that
-
op, said capacitor Cs, and said leakage inductivity Ls are matched according to an upper bound for said operating frequency, such that
-
5. Power converter according to claim 1, wherein the operating frequency is chosen substantially higher than a series resonance frequency defined by the series capacitor and the leakage inductivity Ls as
-
π 1 L s C s , such that the leakage inductivity Ls limits said output current.
-
-
6. Power converter according to claim 5, wherein said operating frequency ƒ
- op, said capacitor Cs, and said leakage inductivity Ls are matched such that an input impedance of said resonant circuit presents an inductive character.
-
7. Power converter according to claim 1, wherein said transformer is a planar transformer.
-
8. Power converter according to claim 7, wherein said leakage inductivity Ls is realized by shifting the center of a spiral primary winding of said transformer with respect to the center of a spiral secondary winding of said transformer.
-
9. Power converter according to claim 1, wherein said leakage inductivity Ls is realized by different dimensions of a primary and a secondary spiral winding of said transformer.
-
10. Power converter according to claim 7, wherein said leakage inductivity Ls is realized as a combination
of shifting the centers of a primary and a secondary winding with respect to each other, and of different dimensioning of said primary and secondary windings. -
11. Power converter according to claim 7, wherein said primary and secondary windings of said transformer are integrated in a printed circuit board, PCB, in a planar manner and a solid PCB layer is disposed between said primary and secondary windings.
-
12. Power converter according to claim 11, wherein planar magnetic cores are disposed adjacent to the flat side of the arrangement consisting of primary windings, solid PCB layer, and secondary winding.
-
13. Power converter according to claim 12, wherein said planar magnetic cores consist of ferrite tiles.
-
14. Power converter according to claim 12, wherein said magnetic cores are formed by highly permeable metal foil.
-
15. Power converter according to claim 14, wherein said highly permeable metal foil is made of NiFe or a mu-metal.
-
16. Power converter according to claim 12, wherein said magnetic cores are made from amorphous iron.
-
17. Power converter according to claim 12, wherein said magnetic cores are made from nanocrystalline iron.
-
18. Power converter according to claim 12, wherein the magnetic cores are structured by providing slots in the magnetic cores, said slots being parallel to magnetic field lines guided within the magnetic cores.
-
19. Power converter according to claim 11, wherein said capacitor Cs is integrated in the PCB.
-
20. Power converter according to claim 1, wherein said power converter is mounted in a grove formed at one side of a heat sink.
-
21. Power converter according to claim 11, wherein said PCB is mounted directly to said heat sink.
-
22. Power converter according to 11, wherein said PCB is made from a thermally highly conducting material.
-
23. Power converter according to claim 11, wherein capacitors having high nominal values are avoided.
-
24. Power converter according to claim 1, further comprising
a first AC-to-DC rectifier connectable to an AC mains supply; a second AC-to-DC rectifier connectable to an electric consumer.
-
25. Power converter according to claim 24, wherein said first AC-to-DC rectifier produces a rectified voltage and a superposed ripple voltage, said ripple voltage having a frequency that is the double of the frequency of the voltage of said AC mains supply.
-
26. Power converter according to 24, wherein the current drawn by said first AC-to-DC rectifier from said AC mains supply is substantially sinusoidal with a frequency equal to the frequency of the voltage of said AC mains supply.
-
27. Power converter according to claim 24, wherein said electric consumer has a diode-like current-voltage characteristic.
-
28. Large Area Light Source (LALS) lamp comprising a power converter according to claim 1.
-
29. Large area light source comprising light emitting diodes as illuminants and comprising a power converter for receiving an input current at an input voltage and for providing an output current at an output voltage, said power converter comprising:
-
a transformer having a primary and at least one secondary side, the transformer showing a mutual inductivity Lm and a leakage inductivity Ls; a least one switching device being operated at an operating frequency fop at the primary side of said transformer; and
a capacitor Cs at the primary side of said transformer, said capacitor forming a resonant circuit with the leakage inductivity Ls of said transformer. - View Dependent Claims (30, 31, 32, 33, 34, 35)
-
Specification