Power Measurement In A Two-Wire Load Control Device

Patent metadata

Field	Value
Publication number	US-2016124453-A1
Application number	US-201614991133-A
Country	US
Kind code	A1
Filing date	Jan 8, 2016
Priority date	Sep 14, 2012
Publication date	May 5, 2016
Grant date	—

Abstract

A two-wire load control device may be configured to compute an accurate estimate of real-time power consumption by a load that is electrically connected to, and controlled by, the two-wire load control device. The load control device may be adapted to measure a voltage drop across the device during a first portion of a half-cycle of an AC waveform provided to the device. The device may be further configured to estimate a voltage drop across the load during the second portion of the half-cycle. The estimated voltage drop may be based on the measured voltage drop. The device may be further configured to measure a current supplied to the load during a second portion of the half-cycle. The device may be configured to estimate power consumed by the load based on the measured current and the estimated voltage drop.

First claim

What is claimed:

1 . A two-wire lighting control device for controlling an amount of power delivered from an alternating current (AC) power source to a lighting load, the lighting control device comprising:
a controllably conductive device configured to be coupled in series electrical connection between the AC power source and the lighting load; a control circuit configured to render the controllably conductive device non-conductive during a first portion of a half-cycle of an AC waveform and render the controllably conductive device conductive during a second portion of the half-cycle to control the amount of power delivered to the lighting load; a voltage measuring circuit configured to measure a voltage across the two-wire lighting control device during the first portion of the half-cycle; a signal generator configured to generate a complementary voltage waveform that approximates a voltage across the lighting load during the second portion of the half-cycle, wherein the complementary voltage waveform is based on the voltage measured across the two-wire lighting control device during the first portion of the half-cycle; and a current measuring circuit configured to measure a current supplied to the lighting load from the two-wire load control device during the second portion of the half-cycle; wherein the control circuit is further configured to compute an estimated amount of power consumed by the lighting load based on the complementary voltage waveform and the current supplied to the lighting load during the second portion of the half-cycle.

2 . The two-wire lighting control device of claim 1 , wherein the two-wire lighting control device comprises a dimmer.

3 . The two-wire lighting control device of claim 1 , wherein the controllably conductive device comprises a triac.

4 . The two-wire lighting control device of claim 1 , wherein the control circuit is configured to control the controllably conductive device using forward phase control to control the amount of power delivered to the lighting load.

5 . The two-wire lighting control device of claim 1 , wherein the lighting load is a lighting load.

6 . The two-wire lighting control device of claim 1 , wherein the voltage measuring circuit comprises a voltage divider.

7 . The two-wire lighting control device of claim 1 , wherein the current measuring circuit comprises a micro-ohm resistor.

8 . The two-wire lighting control device of claim 1 , wherein the control circuit is configured to report the estimated amount of power consumed by the load.

9 . The two-wire lighting control device of claim 1 , wherein the complementary voltage waveform comprises a step-sine wave.

10 . The two-wire lighting control device of claim 1 , wherein the complementary voltage waveform comprises a square wave.

11 . A two-wire lighting control device for controlling an amount of power delivered from an alternating current (AC) power source to a lighting load, the load control device comprising:
a controllably conductive device configured to be coupled in series electrical connection between the AC power source and the lighting load; and a control circuit configured to:
control the amount of power delivered to the lighting load by rendering the controllably conductive device non-conductive during a first portion of a half-cycle of an AC waveform and rendering the controllably conductive device conductive during a second portion of the half-cycle;
measure a voltage across the two-wire lighting control device during the first portion of the half-cycle;
compute an estimated voltage across the load during a second portion of the half-cycle based on the voltage measured across the two-wire lighting control device during the first portion of the half-cycle;
measure a current supplied to the lighting load during the second portion of the half-cycle; and
compute, based on the estimated voltage and the measured current, an estimated power consumed by the lighting load during the second portion of the half-cycle.

12 . The two-wire lighting control device of claim 11 , wherein the control circuit is further adapted to report the estimated power consumed by the load via a communication circuit.

13 . The two-wire lighting control device of claim 11 , wherein the estimated voltage has a step-sine waveform.

14 . The two-wire lighting control device of claim 11 , wherein the estimated voltage has a square waveform.

15 . The two-wire lighting control device of claim 11 , wherein the two-wire lighting control device comprises a dimmer.

16 . The two-wire lighting control device of claim 11 , wherein the controllably conductive device comprises a triac.

17 . The two-wire lighting control device of claim 11 , wherein the control circuit is configured to control the controllably conductive device using forward phase control to control the amount of power delivered to the lighting load.

18 . A method for estimating power consumption of a lighting load using a two-wire lighting control device, the two-wire lighting control device configured to control an amount of power delivered from an alternating current (AC) power source to the lighting load, the lighting control device having a controllably conductive device that is configured to operate in a non-conductive state during a first portion of a half-cycle of an AC waveform and in a conductive state during a second portion of the half-cycle, the method comprising:
measuring a voltage across the two-wire lighting control device during a first portion of the half-cycle; computing an estimated voltage across the lighting load during a second portion of the half-cycle based on the voltage measured across the two-wire lighting control device during the first portion of the half-cycle; measuring a current supplied to the lighting load during the second portion of the half-cycle; and computing, based on the estimated voltage and the measured current, an estimated power consumed by the lighting load during the second portion of the half-cycle.

19 . The method of claim 18 , further comprising reporting the estimated amount of power consumed by the lighting load.

20 . The method of claim 18 , wherein computing the estimated voltage across the lighting load during the second portion of the half-cycle comprises generating a complementary voltage waveform that approximates the voltage across the lighting load during the second portion of the half-cycle, the complementary voltage waveform based on the voltage measured across the two-wire load control device during the first portion of the half-cycle, and the complementary voltage waveform comprising a step-sine wave or a square wave.

Assignees

• Lutron Electronics Co

Inventors

• Blakeley Matthew Robert
• Zotter William

Classifications

• G05F1/12

  wherein the variable actually regulated by the final control device is AC (G05F1/625 takes precedence) · CPC title

• G01R21/133

  by using digital technique · CPC title

• H05B39/04

  Controlling · CPC title

• G06F1/26

  Power supply means, e.g. regulation thereof (for memories G11C) · CPC title

• G05F1/66 Primary

  Regulating electric power · CPC title