Method and apparatus for phase-controlling a load
A load control device may control the amount of power provided to an electrical load utilizing a phase control signal that operates in a reverse phase control mode, a center phase control mode, and a forward phase control mode. A load control device may be configured to determine that the electrical load should be operated via a phase control signal operating in a forward phase-control mode. After determining to operate the electrical load via the phase control signal in the forward phase-control mode, the load control device may provide the phase control signal in a reverse phase-control mode for a predetermined period of time to the electrical load, for example, to charge a bus capacitor of the electrical load. Subsequently, the load control device may be configured to switch the phase control signal to the forward phase-control mode and provide the phase control signal in the forward phase-control mode to the electrical load.
1. A load control device comprising:
a controller configured to control an amount of power delivered from an alternating current (AC) power source to an electrical load, wherein at a transition of the electrical load from an off state to an on state, the controller is further configured to:
provide a first line cycle of a phase control signal, the first line cycle characterized by a first turn-on event and a first conduction time;
subsequent to providing the first line cycle, provide a second line cycle of the phase control signal, the second line cycle characterized by a second turn-on event and a second conduction time, the second turn-on event greater than the first turn-on event;
subsequent to providing the second line cycle, provide a third line cycle of the phase control signal, the third line cycle characterized by a third turn-on event and a third conduction time, the third turn-on event greater than the second turn-on event; and
maintain subsequent line cycles of the phase control signal in accordance with the third turn-on event;
wherein the first conduction time, the second conduction time, and the third conduction time are substantially the same.
2. The load control device of claim 1 , wherein the controller is further configured to:
determine to operate the electrical load using a forward phase control signal prior to providing the first line cycle of the phase control signal.
3. The load control device of claim 1 , wherein the first phase control signal charges a bus capacitor of the electrical load.
4. The load control device of claim 1 , wherein the first phase control signal is a reverse phase control signal.
5. The load control device of claim 1 , wherein the second phase control signal is a center phase control signal.
6. The load control device of claim 1 , wherein the third phase control signal is a forward phase control signal.
7. A load control device comprising:
a controller configured to control an amount of power delivered from an alternating current (AC) power source to an electrical load, wherein at a transition of the electrical load from an off state to an on state, the controller is further configured to:
provide a first line cycle of a phase control signal, the first line cycle characterized by a first turn-on event and a first RMS voltage value;
subsequent to providing the first line cycle, provide a second line cycle of the phase control signal, the second line cycle characterized by a second turn-on event and a second RMS voltage value, the second turn-on event greater than the first turn-on event;
subsequent to providing the second line cycle, provide a third line cycle of the phase control signal, the third line cycle characterized by a third turn-on event and a third RMS voltage value, the third turn-on event greater than the second turn-on event; and
maintain subsequent line cycles of the phase control signal in accordance with the third turn-on event;
wherein the first RMS voltage value, the second RMS voltage value, and the third RMS voltage value are substantially the same.
8. The load control device of claim 7 , wherein the controller is further configured to:
determine to operate the electrical load using a forward phase control signal prior to providing the first line cycle of the phase control signal.
9. The load control device of claim 7 , wherein the first phase control signal charges a bus capacitor of the electrical load.
10. The load control device of claim 7 , wherein the first phase control signal is a reverse phase control signal.
11. The load control device of claim 7 , wherein the second phase control signal is a center phase control signal.
12. The load control device of claim 7 , wherein the third phase control signal is a forward phase control signal.
13. A method for controlling an amount of power delivered from an alternating current (AC) power source to an electrical load by a load control device at a transition of the electrical load from an off state to an on state, the method comprising:
providing a first line cycle of a phase control signal, the first line cycle characterized by a first turn-on event and a first conduction time;
subsequent to providing the first line cycle, providing a second line cycle of the phase control signal, the second line cycle characterized by a second turn-on event and a second conduction time, the second turn-on event greater than the first turn-on event;
subsequent to providing the second line cycle, providing a third line cycle of the phase control signal, the third line cycle characterized by a third turn-on event and a third conduction time, the third turn-on event greater than the second turn-on event; and
maintaining subsequent line cycles of the phase control signal in accordance with the third turn-on event;
wherein the first conduction time, the second conduction time, and the third conduction time are substantially the same.
14. The method of claim 13 , further comprising:
determining to operate the electrical load using a forward phase control signal prior to providing the first line cycle of the phase control signal.
15. The method of claim 13 , wherein the first phase control signal charges a bus capacitor of the electrical load.
16. The method of claim 13 , wherein the first phase control signal is a reverse phase control signal.
17. The method of claim 13 , wherein the second phase control signal is a center phase control signal.
18. The method of claim 13 , wherein the third phase control signal is a forward phase control signal.
19. A method for controlling an amount of power delivered from an alternating current (AC) power source to an electrical load by a load control device at a transition of the electrical load from an off state to an on state, the method comprising:
providing a first line cycle of a phase control signal, the first line cycle characterized by a first turn-on event and a first RMS voltage value;
subsequent to providing the first line cycle, providing a second line cycle of the phase control signal, the second line cycle characterized by a second turn-on event and a second RMS voltage value, the second turn-on event greater than the first turn-on event;
subsequent to providing the second line cycle, providing a third line cycle of the phase control signal, the third line cycle characterized by a third turn-on event and a third RMS voltage value, the third turn-on event greater than the second turn-on event; and
maintain subsequent line cycles of the phase control signal in accordance with the third turn-on event;
wherein the first RMS voltage value, the second RMS voltage value, and the third RMS voltage value are substantially the same.
20. The method of claim 19 , further comprising:
determining to operate the electrical load using a forward phase control signal prior to providing the first line cycle of the phase control signal.
21. The method of claim 19 , wherein the first phase control signal charges a bus capacitor of the electrical load.
22. The method of claim 19 , wherein the first phase control signal is a reverse phase control signal.
23. The method of claim 19 , wherein the second phase control signal is a center phase control signal.
24. The method of claim 19 , wherein the third phase control signal is a forward phase control signal.