Controlling a controllably conductive device based on zero-crossing detection

Patent metadata

Field	Value
Publication number	US-11056304-B2
Application number	US-201916578929-A
Country	US
Kind code	B2
Filing date	Sep 23, 2019
Priority date	Oct 4, 2013
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

A load control device may control power delivered to an electrical load from an AC power source. The load control device may include a controllably conductive device adapted to be coupled in series electrical connection between the AC power source and the electrical load, a zero-cross detect circuit configured to generate a zero-cross signal representative of the zero-crossings of an AC voltage. The zero-cross signal may be characterized by pulses occurring in time with the zero-crossings of the AC voltage. The load control device may include a control circuit operatively coupled to the controllably conductive device and the zero cross detect circuit. The control circuit may be configured to identify a rising-edge time and a falling-edge time of one of the pulses of the zero-cross signal, and may control a conductive state of the controllably conductive device based on the rising-edge time and the falling-edge time of the pulse.

First claim

What is claimed:

1. A load control device for controlling power delivered to an electrical load from an AC power source, the load control device comprising:
a controllably conductive device couplable in series between the AC power source and the electrical load, the controllably conductive device to provide a switched AC voltage to the electrical load;
a zero-cross detect circuit configured to generate a zero-cross signal representative of zero-crossings of an AC voltage, the zero-cross signal characterized by a plurality of pulses occurring in time with the zero-crossings of the AC voltage; and
a control circuit operatively coupled to the controllably conductive device and the zero-cross detect circuit and configured to:
identify a rising-edge time and a falling-edge time of one of the pulses of the zero-cross signal;
determine an actuation adjustment time period using an actuation delay time period and an average contact-bounce duration;
store the determined actuation adjustment time period value in a memory circuit;
initiate a transition of the conductive state of the controllably conductive device at the conclusion of the determined actuation adjustment time period;
monitor the switched voltage to detect at least one of a rising-edge of the switched AC voltage or a falling-edge of the switched AC voltage; and
determine whether the at least one of the rising-edge of the switched AC voltage or the falling-edge of the switched AC voltage occurs within a defined error window.

2. The load control device of claim 1 , wherein to determine the relay actuation adjustment time period using the relay-actuation delay time period and the average relay contact-bounce duration, the control circuit configured to further:
determine the actuation adjustment time period as the difference between a full line cycle of the AC voltage and a sum of the actuation delay time period, the average contact-bounce duration, and one-half of the average contact-bounce duration.

3. The load control device of claim 1 :
wherein to transition the conductive state of the controllably conductive device, the control circuit configured to further:
transition the controllably conductive device to a conductive state;

wherein to monitor the switched AC voltage to detect at least one of the rising-edge of the switched AC voltage or the falling-edge of the switched AC voltage, the control circuit configured to further:
detect the falling-edge of the switched AC voltage; and

wherein to determine whether the at least one of the rising-edge of the switched AC voltage or the falling-edge of the switched AC voltage occurs within a defined error window, the control circuit to further:
determine whether the falling-edge of the switched AC voltage occurs within the defined error window.

4. The load control device of claim 3 :
wherein responsive to the determination that the falling-edge of the switched AC voltage occurs within the defined error window, the control circuit to further:
determine a new closed actuation adjustment time period; and
store the determined new closed actuation adjustment time period as the actuation adjustment time period in the memory circuit.

5. The load control device of claim 1 :
wherein the transition of the conductive state of the controllably conductive device includes a transition of the controllably conductive device to a non-conductive state; and
wherein to monitor the switched AC voltage to detect at least one of the rising-edge of the switched AC voltage or the falling-edge of the switched AC voltage, the control circuit to further:
detect the rising-edge of the switched AC voltage; and

wherein to determine whether the at least one of the rising-edge of the switched AC voltage or the falling-edge of the switched AC voltage occurs within a defined error window, the control circuit to further:
determine whether the rising-edge of the switched AC voltage occurs within the defined error window.

6. The load control device of claim 5 :
wherein responsive to the determination that the rising-edge of the switched AC voltage occurs within the defined error window, the control circuit to further:
determine a new open actuation adjustment time period; and
store the determined new open actuation adjustment time period as the actuation adjustment time period in the memory circuit.

7. A load control method, comprising:
identifying, by a control circuit operatively coupled to a controllably conductive device and a zero-cross detect circuit, a rising-edge time and a falling-edge time of one or more pulses of the zero-cross detect circuit responsive to application of an alternating current (AC) supply voltage to the zero-cross detect circuit;
determining, by the control circuit, an actuation adjustment time period using an actuation delay time period and an average contact-bounce duration;
storing the determined actuation adjustment time period value in a memory circuit operatively coupled to the control circuit;
initiating, by the control circuit, a transition of the conductive state of the controllably conductive device at the conclusion of the determined actuation adjustment time period;
monitoring, by the control circuit, a switched AC voltage to detect at least one of a rising-edge of the switched AC voltage or a falling-edge of the switched AC voltage; and
determining, by the control circuit, whether the at least one of the rising-edge of the switched AC voltage or the falling-edge of the switched AC voltage falls within a defined error window.

8. The method of claim 7 , wherein determining the actuation adjustment time period using the actuation delay time period and the average contact-bounce duration, further comprises:
determining, by the control circuit, the actuation adjustment time period as the difference between a full line cycle of the AC supply voltage and a sum of the actuation delay time period, the average contact-bounce duration, and one-half of the average contact-bounce duration.

9. The method of claim 7 :
wherein initiating the transition of the conductive state of the controllably conductive device at the conclusion of the determined actuation adjustment time period further comprises:
initiating, by the control circuit, a transition of the conductive state of the controllably conductive device to a conductive state at the conclusion of the determined actuation adjustment time period;

wherein monitoring the switched AC voltage to detect at least one of the rising-edge of the switched AC voltage or the falling-edge of the switched AC voltage further comprises:
monitoring, by the control circuit, the switched AC voltage to detect the falling-edge of the switched voltage; and

wherein determining whether the at least one of the rising-edge of the switched AC voltage or the falling-edge of the switched AC voltage falls within a defined error window further comprises:
determining, by the control circuit, whether the falling-edge of the switched AC voltage falls within the defined error window.

10. The method of claim 9 , further comprising:
determining, by the control circuit, a new closed actuation adjustment time period responsive to a determination that the falling-edge of the switched AC voltage falls within the defined error window; and
storing, by the control circuit, the determined new closed actuation adjustment time period as the actuation adjustment time period in the memory circuit.

11. The method of claim 7 :
wherein initiating the transition of the conductive state of the controllably conductive device at the conclusion of the determined actuation adjustment time period further comprises:
initiating, by the control circuit,

Assignees

• Lutron Tech Co Llc

Inventors

• Lenig Robert W
• Sizemore Michael
• Thaler Joshua W
• Macadam Russell L

Classifications

• H01H47/18 Primary

  for introducing delay in the operation of the relay (short-circuited conducting sleeves, bands or discs H01H50/46) · CPC title

• H01H9/56

  for ensuring operation of the switch at a predetermined point in the AC cycle · CPC title