METHOD AND CONTROL CIRCUIT FOR ACTUATING A THYRISTOR OR TRIAC

摘要

A triac (1) is triggered by a control circuit (4) by means of a gate current pulse (IP1) after a voltage zero crossing (tN0) of an alternating voltage source (3). In a setting phase (P10), the control circuit (4) determines a triggering pulse duration (TL) of the gate current pulse (IP1) for triggering the triac (1) such that the current (IR) through the triac (1) reaches at least a latching current value (IL) after the end of the gate current pulse (IP1). In an operating phase (P20), the control circuit (4) actuates the triac (1) by means of a gate current pulse (IP1) having the determined triggering pulse duration (TL) after a voltage zero crossing (tN0) of the alternating voltage source (3) and subsequently monitors a current flow through the triac (1) in order to adjust the determined triggering pulse duration (TL) if necessary.