Load control device for high-efficiency loads
First Claim
1. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
- a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the thyristor having a gate for conducting a gate current to render the thyristor conductive;
a gate coupling circuit coupled to conduct the gate current through the gate of the thyristor;
a controllable switching circuit coupled between the gate coupling circuit and the gate of the thyristor for conducting the gate current when the controllable switching circuit is conductive; and
a control circuit operable to render the controllable switching circuit conductive and to control the gate coupling circuit to conduct the gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, the control circuit continuing to control the gate coupling circuit, such that the gate coupling circuit is able to conduct the gate current again after the firing time, the control circuit rendering the controllable switching circuit non-conductive before the end of the half-cycle, such that the gate coupling circuit is not able to conduct the gate current through the gate of the thyristor after the controllable switching circuit becomes non-conductive.
2 Assignments
0 Petitions
Accused Products
Abstract
A two-wire load control device (such as, a dimmer switch) for controlling the amount of power delivered from an AC power source to an electrical load (such as, a high-efficiency lighting load) includes a thyristor coupled between the source and the load, a gate coupling circuit coupled between a first main load terminal and the gate of the thyristor, and a control circuit coupled to a control input of the gate coupling circuit. The control circuit generates a drive voltage for causing the gate coupling circuit to conduct a gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, and to allow the gate coupling circuit to conduct the gate current at any time from the firing time through approximately the remainder of the half cycle, where the gate coupling circuit conducts approximately no net average current to render and maintain the thyristor conductive.
112 Citations
59 Claims
-
1. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
-
a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the thyristor having a gate for conducting a gate current to render the thyristor conductive; a gate coupling circuit coupled to conduct the gate current through the gate of the thyristor; a controllable switching circuit coupled between the gate coupling circuit and the gate of the thyristor for conducting the gate current when the controllable switching circuit is conductive; and a control circuit operable to render the controllable switching circuit conductive and to control the gate coupling circuit to conduct the gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, the control circuit continuing to control the gate coupling circuit, such that the gate coupling circuit is able to conduct the gate current again after the firing time, the control circuit rendering the controllable switching circuit non-conductive before the end of the half-cycle, such that the gate coupling circuit is not able to conduct the gate current through the gate of the thyristor after the controllable switching circuit becomes non-conductive. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
-
-
23. A load control circuit for controlling the amount of power delivered from an AC power source to an electrical load to a desired amount of power, the load control circuit comprising:
-
a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the thyristor having a gate for conducting a gate current to render the thyristor conductive; a gate coupling circuit coupled to conduct the gate current through the gate of the thyristor; a controllable switching circuit coupled between the gate coupling circuit and the gate of the thyristor for conducting the gate current when the controllable switching circuit is conductive; wherein the controllable switching circuit is rendered conductive and the gate coupling circuit is rendered conductive to conduct the gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, the gate coupling circuit maintained conductive, such that the gate coupling circuit is able to conduct the gate current again after the firing time during the half-cycle, the controllable switching circuit rendered non-conductive before the end of the half-cycle, such that the gate coupling circuit is not able to conduct the gate current through the gate of the thyristor. - View Dependent Claims (24, 25, 26, 27)
-
-
28. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
-
a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the thyristor having a gate for conducting a gate current to render the thyristor conductive and characterized by a rated holding current; a gate coupling circuit coupled to conduct the gate current through the gate of the thyristor; and a control circuit operable to control the gate coupling circuit to conduct the gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, the control circuit continuing to control the gate coupling circuit, such that the gate coupling circuit is able to conduct the gate current again after the firing time; wherein the gate coupling circuit is prevented from conducting the gate current too close to the end of the half-cycle to prevent the thyristor from being rendered conductive at the beginning of the next half-cycle, the gate coupling circuit also operable to conduct the load current, such that the combination of the thyristor and the gate coupling circuit are operable to conduct the load current through the load independent of the rated holding current of the thyristor. - View Dependent Claims (29, 30, 31, 32, 33, 34)
-
-
35. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
-
a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the thyristor having a gate for conducting a gate current to render the thyristor conductive; a gate coupling circuit comprising two MOS-gated transistors operatively coupled in anti-series connection between the first main load terminal and the gate of thyristor for conducting the gate current through the gate of the thyristor when the anti-series combination of the MOS-gated transistors is conductive; and a control circuit operable to cause the anti-series combination of the MOS-gated transistors to conduct the gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source; wherein the control circuit is operable to cause the anti-series combination of the MOS-gated transistors to remain conductive to conduct the gate current again after the firing time and before the end of the half-cycle. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
-
-
53. A load control device for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
-
a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the thyristor having a gate for conducting a gate current to render the thyristor conductive and characterized by a rated holding current; a gate coupling circuit coupled to conduct the gate current through the gate of the thyristor; and a control circuit operable to cause the gate coupling circuit to conduct the gate current to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, the control circuit continuing to control the gate coupling circuit, such that the gate coupling circuit is able to conduct the gate current again after the firing time; wherein the gate coupling circuit is also operable to conduct the load current if the magnitude of the load current falls below the rated holding current of the thyristor. - View Dependent Claims (54, 55, 56, 57, 58)
-
-
59. A load control circuit for controlling the amount of power delivered from an AC power source to an electrical load, the load control device comprising:
-
a thyristor having first and second main load terminals adapted to be coupled in series electrical connection between the AC power source and the electrical load for conducting a load current from the AC power source to the electrical load, the thyristor having a gate for conducting a gate current to render the thyristor conductive and characterized by a rated holding current; and a gate coupling circuit coupled to conduct the gate current through the gate of the thyristor to thus render the thyristor conductive at a firing time during a half cycle of the AC power source, the gate coupling circuit maintained conductive, such that the gate coupling circuit is able to conduct the gate current again after the firing time; wherein the gate coupling circuit is also operable to conduct the load current if the magnitude of the load current falls below the rated holding current of the thyristor.
-
Specification