Synchronous regulation for LED string driver
A light emitting diode (LED) based luminaire driving arrangement constituted of: a switched driver; a plurality of LED based luminaries arranged to receive power from the switched driver; at least one electronically controlled switch in series with at least one of the plurality of LED based luminaries and arranged to alternatively pass current through the at least one LED based luminaire when closed and prevent the flow of current through the at least one LED based luminaire when opened; and at least one synchronous driver in communication with the at least one electronically controlled switch, the at least one synchronous driver arranged to close the at least one electronically controlled switch only when the switched driver is actively supplying power.
1. A light emitting diode (LED) based luminaire driving arrangement comprising:
a switched power conversion stage having a power transformer with a primary and at least one secondary winding, the switched power conversion stage arranged to produce a predetermined voltage across the secondary winding;
a plurality of LED based luminaries arranged to receive power in parallel from said at least one secondary winding of said switched power conversion stage;
a balancer constituted of a plurality of balancing transformers, each of said plurality of balancing transformers exhibiting a first winding and a second winding magnetically coupled to said first winding, said first winding of each of said balancing transformers connected in series with a particular one of the plurality of LED based luminaries and said second windings of said plurality of balancing transformers connected in a closed serial loop;
an electronically controlled switch in series with said plurality of parallel LED based luminaries and arranged to alternatively pass current through said plurality of parallel LED based luminaries when closed and prevent the flow of current through said plurality of parallel LED based luminaries when opened; and
a synchronous driver in communication with said electronically controlled switch, said synchronous driver arranged to close said electronically controlled switch only when said switched power conversion stage is actively supplying power via said at least one secondary winding and further comprising a plurality of capacitors, each of said plurality of capacitors switch-ably connected in parallel with a particular one of the plurality of parallel LED based luminaries LEDs.
2. The LED based luminaire driving arrangement according to claim 1 , wherein each of said plurality of LED based luminaries is constituted of a string of serially connected LEDs.
3. The LED based luminaire driving arrangement according to claim 1 , further comprising a plurality of capacitors, each of said plurality of capacitors connected in parallel with a particular one of the plurality of parallel LED based luminaries.
4. The LED based luminaire driving arrangement according to claim 1 , wherein said power transformer of said switched power conversion stage comprises a plurality of secondary windings, each of said plurality of LED based luminaries arranged to receive power from a common one of said secondary windings thereby receiving power from said switched power conversion stage, said predetermined voltage controlled responsive to the voltage developed across a non-common one of said secondary windings.
5. The LED based luminaire driving arrangement according to claim 1 , wherein said synchronous driver is leading edge modulated.
6. A method of driving a plurality of light emitting diode (LED) based luminaries, the method comprising:
providing power with a predetermined voltage across at least one secondary winding of a switched power conversion stage;
switchably driving said plurality of LED based luminaries synchronously with said provided power from said at least one secondary winding only when said switched power conversion stage is actively supplying power via said at least one secondary winding, wherein an end of each of said plurality of LED based luminaries is connected to a common node; and
balancing the current flow through each of said parallel connected LED based luminaries by providing a balancer constituted of a plurality of balancing transformers, each of said plurality of balancing transformers exhibiting a first winding and a second winding magnetically coupled to said first winding, said first winding of each of said balancing transformers connected in series with a particular one of the plurality of LED based luminaries and said second windings of said plurality of balancing transformers connected in a closed serial loop and further comprising filtering the voltage drop across each of the plurality of LEDs by providing a plurality of capacitors, each of said plurality of capacitors switch-ably connected in parallel with a particular one of the plurality of LEDs.
7. The method of claim 6 , wherein each of said plurality of LED based luminaries is constituted of a string of serially connected LEDs.
8. The method according to claim 6 , further comprising filtering the voltage drop across each of the plurality of LED based luminaries by providing a plurality of capacitors, each of said plurality of capacitors connected in parallel with a particular one of the provided plurality of LED based luminaries.
9. The method according to claim 6 , wherein the leading edge of said switchably driving is modulated.