Low Voltage Outdoor Lighting Power Source and Control System

• US 20100084985A1
• Filed: 09/22/2009
• Published: 04/08/2010
• Est. Priority Date: 10/02/2008
• Status: Active Grant

• Current Assignee: Hunter Industries Incorporated
• Original Assignee: Hunter Industries Incorporated
• Inventors: Woytowitz, Peter J.
• Granted Patent: US 8,773,030 B2
• Time in Patent Office: Days
• US Class Current: 315/210
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/39 Circuits containing inverter bridges
• CPC Class Codes: H05B 47/185 via power line carrier transmission
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A power source and control system is particularly suited for use in an outdoor landscape lighting system. The power source and control system includes at least one switching mode AC-to-DC power supply having an additional output stage for efficiently converting the DC output signal into another relatively low frequency AC signal for transmission to a plurality of buried power conductors. A Manchester encoded control signal is encoded at a relatively high frequency onto the AC signal sent over the buried power conductors so that intelligent LED lighting fixtures can be powered by the AC signal and selectively have their intensity changed when they decode the control signal.

Claims

1. A power source and control system for use in an outdoor lighting system, comprising:

a power source input for accepting a first alternating-current (AC) voltage;

a first rectifier circuit coupled to the power source input configured to produce a first direct-current (DC) output voltage;

a first switching circuit coupled to the first rectifier circuit and configured to produce a second AC output voltage;

a transformer coupled to the first switching circuit and configured to produce a third AC output voltage;

a second rectifier circuit coupled to the transformer and configured to produce a second DC output voltage;

a second switching circuit coupled to the second rectifier circuit and configured to produce a fourth AC output voltage at a first frequency;

a power source output for providing a connection between the fourth AC output voltage and at least two electrical conductors; and

an encoder circuit configured to encode an encoded control signal on the fourth AC output voltage at a second frequency higher than the first frequency.

2. The system of claim 1 wherein:

the average DC value of the fourth AC output voltage is substantially zero.

3. The system of claim 2 wherein the second switching circuit includes an H-bridge circuit.

4. The system of claim 1 and further comprising:

one or more Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) switching devices in at least one of the first and second switching circuits.

5. The system of claim 1 and further comprising:

one or more Insulated Gate Bipolar Transistor (IGBT) switching devices in at least one of the first and second switching circuits.

6. The system of claim 1 and further comprising:

one or more the Bipolar Junction Transistor (BJT) switching devices in at least one of the first and second switching circuits.

7. The system of claim 1 wherein the encoded control signal has a Manchester encoding and has a protocol that includes a field identifying a destination and a field identifying a predetermined intensity.

8. The system of claim 1 wherein the protocol includes bits representing a checksum.

9. The system of claim 1 wherein the fourth AC voltage is switched at a frequency of between about 0.5 Hz and about 10 Hz.

10. The system of claim 1 wherein the control signal is encoded at a frequency of between about 100 Hz and about 5 KHz.

11. The system of claim 1 wherein control signal is encoded immediately adjacent a rising edge of the fourth AC voltage signal.

12. An intelligent lighting fixture configured to be coupled to the at least two electrical conductors, comprising:

a rectifier circuit configured to produce a DC output voltage from an alternating current (AC) voltage transmitted on the at least two electrical conductors at a first relatively low frequency;

an illuminator driver coupled to the DC output voltage and configured to produce an illumination output voltage;

an illuminator coupled to the illuminator driver for producing light responsive to the illumination output voltage;

a decoder circuit configured to be coupled to the at least two electrical conductors and adapted to recover an encoded control signal from the AC voltage, the encoded control signal being encoded on the AC voltage at a second relatively high frequency and having a protocol including a field identifying a destination and a field identifying a predetermined intensity; and

a microcontroller coupled to the illuminator driver for controlling the illumination output voltage responsive to the recovered control signal.

13. The lighting fixture of claim 12 wherein the illuminator is selected from the group consisting of incandescent lights, light emitting diodes (LEDs), and Variable-Color Light-Emitting Devices (VCLEDs).

14. The lighting fixture of claim 12 and further comprising:

a stored program executable by the microcontroller for causing illumination output voltage changes adapted to produce changes in VCLED color responsive to the recovered control signal.

15. An outdoor lighting system, comprising:

a power source and control system including a pair of rectifier stages and a pair of switching circuits for generating an AC signal at a first relatively low frequency and for encoding a control signal onto the AC signal at a second relatively high frequency;

a plurality of lighting fixtures configured to be powered by the AC signal and including decoder circuitry that extracts the control signal from the AC signal and control circuitry that controls an intensity of each lighting fixture based on the control signal; and

a plurality of buried conductors connected to supply the AC signal from the power source and control system to the plurality of lighting fixtures.

16. The system of claim 15 wherein the encoded control signal is Manchester encoded and has a protocol that includes a field identifying a destination and a field identifying a predetermined intensity.

17. The system of claim 16 wherein the protocol includes bits representing a checksum.

18. The system of claim 15 wherein the low frequency is between about 0.5 Hz and about 10 Hz.

19. The system of claim 15 wherein the high frequency is between about 100 Hz and about 5 KHz.

20. The system of claim 15 wherein control signal is encoded immediately adjacent a rising edge of the AC signal.