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 gate coupling circuit for conducting a gate current through a gate of the thyristor, and a control circuit for controlling the gate coupling circuit to conduct the gate current through a first current path to render the thyristor conductive at a firing time during a half cycle. The gate coupling circuit is able to conduct the gate current through the first current path again after the firing time, but the gate current is not able to be conducted through the gate from a transition time before the end of the half-cycle until approximately the end of the half-cycle. The load current is able to be conducted through a second current path to the electrical load after the transition time until approximately the end of the half-cycle.

主权项

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 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; and a control circuit operable to control the gate coupling circuit to conduct the gate current through a first current path to 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 through the first current path again after the firing time; wherein the gate current is not able to be conducted through the gate of the thyristor from a transition time before the end of the half-cycle until approximately the end of the half-cycle, the load current able to be conducted from the AC power source to the electrical load through a second current path after the transition time until approximately the end of the half-cycle.