Solid state lighting, drive circuit and method of driving same
First Claim
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1. A system for solid state lighting, comprising:
- a transformer having a primary side and a secondary side, the primary side including at least a first primary inductor, the secondary side including at least a pair of secondary inductors, each of the secondary inductors having a respective node that provides current to a respective one of a pair of strings of solid state light sources and not the other one of the pair of strings of solid state light sources, and the secondary side having a center tap between the pair of secondary inductors that provides a common ground to each of the pair of strings of solid state light sources; and
a drive circuit electrically coupled to drive the primary side of the transformer.
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Abstract
A power converter output stage provides acceptable current matching between sets or strings of solid state light sources (e.g., LEDs) with different forward voltages, and protects the sets or strings from excessive over-current in the case of a light source failing as a short. The sets or strings are electrically coupled across respective inductors of a secondary of a transformer, the sets or strings not electrically in parallel with one another. The secondary of the transformer essentially self balances. The embodiments described employ an LLC resonator converter topology, but could be implemented as part of a Flyback, LLC resonator or other switch mode topology.
191 Citations
20 Claims
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1. A system for solid state lighting, comprising:
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a transformer having a primary side and a secondary side, the primary side including at least a first primary inductor, the secondary side including at least a pair of secondary inductors, each of the secondary inductors having a respective node that provides current to a respective one of a pair of strings of solid state light sources and not the other one of the pair of strings of solid state light sources, and the secondary side having a center tap between the pair of secondary inductors that provides a common ground to each of the pair of strings of solid state light sources; and a drive circuit electrically coupled to drive the primary side of the transformer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A solid state lighting luminaire, comprising:
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a first set of solid state light sources electrically coupled in series with one another; a second set of solid state light sources electrically coupled in series with one another; a transformer having a primary side and a secondary side, the primary side including at least a primary inductor, the secondary side including at least a first secondary inductor and a second secondary inductor, the first set of solid state light sources electrically coupled across the first secondary inductor of the transformer and not across the second secondary inductor of the transformer, and the second set of solid state light sources electrically coupled across the second secondary inductor of the transformer and not across the first secondary inductor of the transformer; and a resonator drive circuit which includes a resonator inductor, a resonator capacitor, a first switch and a second switch, the resonator inductor and the resonator capacitor electrically coupled in series with one another and with the primary inductor of the transformer, the first and the second switch operable to selectively provide a drive signal to the primary inductor of the transformer. - View Dependent Claims (13, 14, 15, 16)
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17. A method of operation in a solid state lighting system which includes a first plurality of solid state light emitters electrically coupled in series and a second set of solid state light emitters electrically coupled in series, and a transformer that includes a primary side and a secondary side that includes a first secondary inductor and a second secondary inductor, the first plurality of solid state light emitters electrically coupled across only the first secondary inductor and the second plurality of solid state light emitters electrically coupled across only the second secondary inductor, the method comprising:
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supplying a number of drive signals to control operation of a first switch to selectively electrically couple an LLC resonator to a voltage source via a first electrically conductive path, the LLC resonator including a resonator inductor, a resonator capacitor and a primary inductor of the transformer, the resonator inductor, the resonator capacitor and the primary inductor electrically coupled in series with one another; and supplying a number of drive signals to control operation of a second switch to selectively electrically couple the LLC resonator to the voltage source via a second electrically conductive path only when the LLC resonator is not electrically coupled to the voltage source via the first electrically conductive path, the second electrically conductive path different from the first electrically conductive path. - View Dependent Claims (18, 19, 20)
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Specification