LED Illumination systems

• US 20110309760A1
• Filed: 05/09/2011
• Published: 12/22/2011
• Est. Priority Date: 05/08/2010
• Status: Active Grant

• Current Assignee: EMD Technologies Inc (Benchmark Electronics Incorporated)
• Original Assignee: Giampaolo Carli, Robert Beland
• Inventors: Beland, Robert, Carli, Giampaolo
• Granted Patent: US 8,710,765 B2
• Time in Patent Office: Days
• US Class Current: 315/201
• CPC Class Codes: H02M 1/4258 using a single converter stage both for correction of AC input power factor and generation of a regulated and galvanically isolated DC output voltage H02M1/4241 takes precedence
• CPC Class Codes: H04B 2203/5458 Monitor sensor; Alarm systems
• CPC Class Codes: H05B 39/04 Controlling
• CPC Class Codes: H05B 39/044 continuously H05B39/042 takes precedence
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• CPC Class Codes: H05B 45/385 using flyback topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• 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

An illumination system includes a power supply having a boost converter operating in the discontinuous conduction mode, a flyback converter operating in the critical conduction mode, and a switch coupled to the flyback converter. Several light emitting diodes receive power from the power supply. The boost converter may include a boost inductor (L_B) and a boost diode (D_B), constructed to perform the boost power factor correction (PFC) function. The flyback converter may includes a flyback inductor (L_FB) and a flyback diode (D_FB) and the power supply may be constructed to turn on the switch around the point where the current flowing in the flyback inductor reaches zero value.

Claims

1. An illumination system, comprising:

a power supply including a boost converter operating in the discontinuous conduction mode, a flyback converter operating in the critical conduction mode, and a switch coupled to said flyback converter; and

several light emitting diodes receiving power from said power supply.

2. The illumination system of claim 1 wherein said boost converter includes a boost inductor and a boost diode, and said flyback converter includes a flyback inductor and a flyback diode and said power supply is constructed to turn on said switch as the current flowing in said flyback inductor reaches zero value.

3. The illumination system of claim 1 wherein all capacitors are non-electrolytic capacitors.

4. The illumination system of claim 1 wherein an output of said flyback converter is used for regulating said power supply.

5. The illumination system of claim 1 wherein said flyback converter includes a capacitor operating in open loop and thus said power supply is controlled without receiving a feedback from said capacitor of said flyback converter.

6. The illumination system of claim 2 wherein said flyback converter provides an output being regulated by a feedback loop.

7. The illumination system of claim 6 wherein said flyback converter is regulated by said feedback loop being a voltage feedback.

8. The illumination system of claim 6 wherein said flyback converter is regulated by said feedback loop being a current feedback.

9. The illumination system of claim 6 wherein said flyback converter is regulated by said feedback loop and an error signal sets a peak current of said flyback inductor (L_FB) that automatically also determines a current flowing in said boost inductor (L_B).

10. The illumination system of claim 1 wherein said flyback converter includes a flyback inductor, a switch, and flyback diode providing flyback-based output regulation and isolation;

and wherein an output from said flyback converter is coupled to an output rectifier and a filter providing an LED current to said several light emitting diodes.

11. An illumination method, comprising the steps of:

providing a power supply including a boost converter, a flyback converter, and a switch coupled to said flyback converter;

operating said boost converter in the discontinuous conduction mode, and operating said flyback converter in the critical conduction mode; and

delivering current to several light emitting diodes.

12. The illumination method of claim 11 including turning on said switch as a current flowing in a flyback inductor of said flyback converter reaches zero value.

13. The illumination method of claim 11 including regulating said power supply by an output of said flyback converter.

14. The illumination method of claim 11, wherein said flyback converter includes a capacitor operating in open loop and thus controlling said power supply without receiving a feedback from said capacitor of said flyback converter.

15. The illumination method of claim 14 including regulating the output from said flyback converter by utilizing a feedback loop.

16. The illumination method of claim 15 including setting a peak current of said flyback inductor (L_FB) by an error signal sets that automatically also determines a current flowing in a boost inductor (L_B) of said boost converter.

17. An illumination system, comprising:

a master power supply including an AC inverter and an amplitude modulator, said master power supply being constructed and arranged to generate high-frequency current provided to a primary wire forming a current-carrying loop;

said amplitude modulator being constructed to amplitude modulate said current at at least two modulation frequencies; and

at least two illumination modules each including several light emitting diodes receiving power by inductive coupling from said current-carrying loop, each said illumination module including a frequency discriminator, responsive to one of said modulation frequencies, constructed to enable control of a DC current to said light emitting diodes and thereby control emission of light from said light emitting diodes.

18. The illumination system of claim 17 wherein said inductive coupling is achieved by an electromagnetic coupling element including a magnetic core arranged to receive said current-carrying loop as a primary wire, and a secondary wire wound around at least a portion of said magnetic core to enable said inductive coupling from said primary wire, said secondary wire being connected to provide current to said light emitting diodes.

19. The illumination system of claim 17, wherein said high-frequency current is in the range of 20 kHz to 100 kHz, and said modulation frequencies are in the range of 1 kHz to 10 kHz.

20. The illumination system of claim 17, wherein said illumination module includes a switch that acts as an on/off shunt for said light emitting diodes.