Load control device for high-efficiency loads

摘要

A load control device for controlling the power delivered from an AC power source to an electrical load includes a thyristor, a first current path for conducting current through a gate terminal of the thyristor, and a control circuit for controlling the first current path to conduct a pulse of current through the gate terminal to render the thyristor conductive at a firing time during a half cycle. The first current path is able to conduct at least one other pulse of current through the gate terminal again after the firing time until, a transition time before the end of the half-cycle, but prevented from conducting pulses of current after the transition time until the end of the half-cycle. The load control device may comprise a second current path for conducting current through the electrical load between the transition time and the end of the half-cycle.

主权项

1. A load control device for controlling power delivered from an AC power source to an electrical load, the load control device comprising:
a thyristor adapted to be electrically coupled between the AC power source and the electrical load, the thyristor having first and second main terminals through which current can be conducted to energize the electrical load and a gate terminal through which current can be conducted to render the thyristor conductive; a first current path electrically coupled between the first main terminal of the thyristor and the gate terminal of the thyristor to conduct current through the gate terminal of the thyristor; a control circuit configured to control the first current path to conduct a pulse of current through the gate terminal of the thyristor to render the thyristor conductive at a firing time during a present half-cycle of the AC power source, the control circuit being configured to control the first current path to allow the first current path to conduct at least one other pulse of current through the gate terminal of the thyristor again after the firing time until a transition time before the end of the present half-cycle; and a second current path electrically coupled between the first and second terminals of the thyristor to conduct current through the electrical load between the transition time and the end of the present half-cycle.