HIGH EFFICIENCY POWER CONTROLLER FOR LUMINAIRE

• US 20150137693A1
• Filed: 11/18/2014
• Published: 05/21/2015
• Est. Priority Date: 11/18/2013
• Status: Active Grant

• Current Assignee: Express Imaging Systems, LLC
• Original Assignee: Express Imaging Systems, LLC
• Inventors: Reed, William G.
• Granted Patent: US 9,414,449 B2
• Time in Patent Office: Days
• US Class Current: 315/201
• CPC Class Codes: H01F 27/24 Magnetic cores
• CPC Class Codes: H02M 1/4208 Arrangements for improving power factor of AC input
• CPC Class Codes: H02M 7/06 using discharge tubes without control electrode or semiconductor devices without control electrode
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: H05B 47/20 Responsive to malfunctions or to light source life; for protection

Abstract

Systems, methods and articles for providing lighting or illumination systems having drive circuits that employ a magnetic amplifier (“mag-amp”) and one or more feedback circuits to form a power converter that powers solid-state light sources (e.g., LEDs). The magnetic amplifier includes one or more magnetic cores which provides a controllable reluctance for magnetic flux. The magnetic amplifier includes one or more power windings which receive energy from an alternating current (AC) supply (e.g., AC mains) and delivers rectified AC current as direct current (DC) to one or more solid-state light sources. The magnetic amplifier includes one or more control windings coupled to a DC control source. The drive circuit may have two or more rectifiers (e.g., solid-state rectifiers) to provide a direct current to drive the solid-state light sources and also to isolate the one or more control windings from interference from the magnetic flux of the one or more power windings.

Claims

1. An illumination system, comprising:

one or more magnetic cores;

one or more control windings, each of the one or more control windings wound around at least a portion of at least one of the one or more magnetic cores;

a control circuit electrically coupled to the one or more control windings, the control circuit controls a flow of direct current through the one or more control windings which causes a biasing magnetic flux in the one or more magnetic cores;

one or more power windings, each of the one or more power windings wound around at least a portion of at least one of the one or more magnetic cores, the one or more power windings which in operation receive alternating current from an alternating current supply;

a plurality of solid-state light sources electrically coupled to the one or more power windings; and

a rectifier electrically coupled to the one or more power windings and to the plurality of solid-state light sources, wherein in operation the rectifier provides a direct current to drive the plurality of solid-state light sources.

2. The illumination system of claim 1 wherein the plurality of solid-state light sources are light emitting diodes (LEDs).

3. The illumination system of claim 1 wherein in operation the one more power windings receive alternating current from the alternating current supply that operates at approximately 50 or 60 Hertz.

4. The illumination system of claim 1, further comprising:

a feedback circuit that communicatively couples a feedback current to the control circuit which controls a flow of direct current through the plurality of solid-state light sources to a defined instantaneous level.

5. The illumination system of claim 4 wherein the feedback circuit is electrically isolated from the plurality of solid-state light sources.

6. The illumination system of claim 4 wherein the control circuit implements a power factor correction transfer function which controls the flow of direct current through the one or more control windings which controls the flow of alternating current through the one or more power windings in a manner which improves the power factor of the illumination system.

7. The illumination system of claim 6 wherein the control circuit receives a measure of at least one of an input voltage or a phase angle of the alternating current supply.

8. The illumination system of claim 6 wherein the control circuit includes at least one microcontroller that implements the power factor correction transfer function.

9. The illumination system of claim 8 wherein the control circuit includes at least one nontransitory processor-readable storage medium that stores the power factor correction transfer function, and which is communicatively coupled to the microcontroller, and wherein the microcontroller receives a measure of at least one of an input voltage or a phase angle of the alternating current supply, and uses the measure to index into a table of direct current control output values and retrieve a direct current control output value that corrects the power factor of the power delivered to the plurality of solid-state light sources.

10. The illumination system of claim 1, further comprising:

a power factor correction capacitor electrically coupled across terminals of the alternating current supply.

11. The illumination system of claim 1 wherein the one or more power windings do not electrically galvanically isolate the plurality of solid-state light sources from the alternating current supply.

12. The illumination system of claim 1 wherein the one or more power windings electrically galvanically isolate the plurality of solid-state light sources from the alternating current supply.

13. The illumination system of claim 1 wherein more than one set of power windings drive a plurality of separated solid-state light sources controlled by one or more common or separate control windings.

14. The illumination system of claim 1, further comprising:

a flicker control circuit comprising a passive resonating circuit electrically coupled to the rectifier to increase a frequency of an output signal of the rectifier to a frequency that is sufficiently high that a flicker from the plurality of solid-state light sources is undetectable by an unaided human eye.

15. The illumination system of claim 1 wherein the rectifier comprises at least two solid-state rectifiers.

16. The illumination system of claim 1 wherein the rectifier comprises at least four solid-state rectifiers.

17. The illumination system of claim 1 wherein the one or more magnetic cores comprises a magnet core having a plurality of legs, the one or more control windings wound around a first leg, the one or more power windings wound around a second leg different from the first leg.

18. The illumination system of claim 1 wherein the one or more magnetic cores comprises at least two magnetic cores, the one or more control windings are wound around at least a portion of each of the at least two magnetic cores, and the one or more power windings are wound around at least a portion of each of the at least two magnetic cores.

19. A drive circuit to drive a plurality of solid-state light sources of an illumination system, the drive circuit comprising:

a magnetic core;

a control windings wound around at least a portion of the magnetic core;

a control circuit electrically coupled to the control winding, the control circuit controls a flow of direct current through the control winding which causes a biasing magnetic flux in the magnetic core;

a power winding wound around at least a portion of the magnetic core;

a rectifier electrically coupled to the power winding and to the plurality of solid-state light sources; and

wherein in operation the power winding receives alternating current from an alternating current supply and delivers direct current to the plurality of solid-state light sources via the rectifier.

20. A method of operation for an illumination system comprising a plurality of solid-state light sources, the method comprising:

receiving an alternating current signal at an input terminal;

rectifying the alternating current signal with a rectifier;

providing the rectified current signal to the plurality of solid-state light sources via one or more power windings wound around one or more magnetic cores; and

selectively controlling a flow of direct current through one or more control windings wound around the one or more magnetic cores to control the rectified current signal provided to the plurality of solid-state light sources.

21. The method of claim 20 wherein receiving an alternating current signal at an input terminal comprises receiving an alternating current signal that operates at approximately 50 or 60 Hertz.

22. The method of claim 20, further comprising:

receiving a feedback signal indicative of direct current that flows through the plurality of solid-state light sources; and

wherein selectively controlling a flow of direct current through one or more control windings comprises selectively controlling a flow of direct current through one or more control windings based at least in part on the received feedback signal.

23. The method of claim 22 wherein receiving a feedback signal indicative of direct current that flows through the plurality of solid-state light sources comprises receiving a feedback signal that is electrically isolated from the plurality of solid-state light sources.

24. The method of claim 20, further comprising:

implementing a power factor correction transfer function which controls the flow of direct current through the one or more control windings which controls the flow of alternating current through the one or more power windings in a manner which improves the power factor of the illumination system.

25. The method of claim 24, further comprising:

receiving a signal indicative of at least one of an input voltage or a phase angle of the alternating current signal.

26. The method of claim 20, further comprising:

increasing a frequency of the rectified current signal with a resonant network including passive electrical elements to reduce a detectability of amplitude variations in the rectified current signal by an unaided human eye as emitted by the plurality of solid-state light sources.

27. The method of claim 20 wherein rectifying the alternating current signal comprises rectifying the alternating current signal with at least two solid-state rectifiers.

28. The method of claim 20 wherein rectifying the alternating current signal comprises rectifying the alternating current signal with at least four solid-state rectifiers.