Power Conversion and Control Systems and Methods for Solid-State Lighting

• US 20140239833A1
• Filed: 05/08/2014
• Published: 08/28/2014
• Est. Priority Date: 10/04/2010
• Status: Active Grant

• Current Assignee: Earl W. Mccune Jr
• Original Assignee: Earl W. Mccune Jr
• Inventors: McCune, Earl W. Jr.
• Granted Patent: US 9,565,726 B2
• Time in Patent Office: Days
• US Class Current: 315/201
• CPC Class Codes: H05B 45/355 Power factor correction [PFC]; Reactive power compensation
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A solid-state lighting system comprises a plurality of light-emitting devices (e.g., light-emitting diodes) and an alternating current to direct current (AC-DC) converter that converts AC power to DC power for powering the plurality of light-emitting devices. The AC-DC converter is configured to perform AC-DC conversion directly, without the need for or use of a bridge rectifier or step-down transformer. According to one aspect of the invention, the light-emitting devices of the solid-state lighting system are autonomous and individually powered by a plurality of DC power supplies generated from the DC power produced by the AC-DC converter. According to another aspect, a plurality of phase-offset dimmer control signals are generated based on waveform distortions in a dimming signal produced by a conventional dimmer switch. The phase-offset dimmer control signals are used to individually control the dimming of the light-emitting devices.

Claims

1. A lighting system, comprising:

one or more light-emitting devices; and

an alternating current to direct current (AC-DC) converter configured to convert an AC input voltage Vin to a DC output voltage Vout for powering said one or more light-emitting devices, said AC-DC converter including a plurality of switches, a comparison circuit configured to determine times when Vin>

Vout and times when Vin<

−

Vout, and a switch control circuit configured to control said plurality of switches based on comparisons performed by said comparison circuit.

2. The lighting system of claim 1, wherein said AC-DC converter is configured to operate as a buck converter during times said comparison circuit determines that Vin>

Vout and as an inverting buck converter during times said comparison circuit determines that Vin<

−

Vout.

3. The lighting system of claim 1, wherein said one or more light-emitting devices comprises a plurality of independently-powered light-emitting devices and said lighting system further comprises a power divider circuit configured to generate a plurality of DC power supplies from power provided by said AC-DC converter, said plurality of DC power supplies used to supply power to said plurality of independently-powered light-emitting devices.

4. The lighting system of claim 1, further comprising a dimmer circuit configured to generate a low-frequency signal having a duty cycle that is dependent upon the magnitude of an analog dim control signal provided by an external dim control switch relative to said DC output voltage rout.

5. The lighting system of claim 4, wherein said dimmer circuit is further configured to upconvert said low-frequency signal to a high-frequency digital dim control signal for controlling dimming of said one or more light-emitting devices, said high-frequency digital dim control signal having a duty cycle that is the same as the duty cycle of said low-frequency signal.

6. A lighting system, comprising:

one or more light-emitting devices; and

an alternating current to direct current (AC-DC) converter configured to convert AC power from an AC power source to DC power, said AC-DC converter including;

a first plurality of switches configured to chop an AC input signal from said AC power source during positive half cycles of the AC input signal,

a second plurality of switches configured to invert and chop said AC input signal during negative half cycles of the AC input signal,

an inductor coupled to one or more switches of said first and second pluralities of switches, and

an output capacitor coupled to one or more switches of said first and second pluralities of switches.

7. The lighting system of claim 6, further comprising a controller having a comparison circuit configured to compare the magnitude of an AC voltage from said AC power source or scaled version thereof to a DC voltage produced by said AC-DC converter, compare the magnitude of said AC voltage or scaled version thereof to the negative of said DC voltage, and produce switch control signals having duty cycles based on said comparisons.

8. The lighting system of claim 7, wherein said controller further comprises dim control circuitry configured to control dimming of light emitted by said one or more light-emitting devices depending on the comparisons performed by said comparison circuit.

9. A lighting system, comprising:

one or more light-emitting devices; and

an alternating current to direct current (AC-DC) converter configured to convert an AC input voltage from an AC power source to a DC voltage, said AC-DC converter including;

an inductor,

a first plurality of switches configured to repeatedly couple and decouple said inductor to and from said AC power source during positive half cycles of said AC input voltage,

a second plurality of switches configured to invert said AC input voltage and repeatedly couple and decouple said inductor to and from said AC power source during negative half cycles of said AC input voltage, and

an output capacitor coupled to one or more switches of said first and second pluralities of switches.

10. The lighting system of claim 9, further comprising a comparison circuit configured to compare the magnitude of said AC input voltage or scaled version thereof to said DC voltage, compare the magnitude of said AC input voltage or scaled version thereof to the negative of said DC voltage, and produce switch control signals having duty cycles based on said comparisons.

11. The lighting system of claim 10, further comprising dim control circuitry configured to control dimming of light emitted by said one or more light-emitting devices depending on the comparisons performed by said comparison circuit.

12. A power conversion and control system for an electrical load, comprising:

an alternating current to direct current (AC-DC) converter configured to convert AC power from an AC power source to DC power;

comparison circuitry configured to compare the magnitude of an AC input voltage from said AC power source or scaled version thereof to the DC output voltage produced at the output of said AC-DC converter, compare the magnitude of said AC input voltage or scaled version thereof to the negative of said DC output voltage, and produce an output signal having a duty cycle based on the comparisons; and

control circuitry configured to control current passing through said electrical load according to the duty cycle of the output signal of said comparison circuitry.