This information is part of the Modelica Standard Library maintained by the Modelica Association.

Simplified model of a triode for alternating current, built from two antiparallel thyristors. thyristor1 has to be fired during the positive halfwave of the voltage. thyristor2 has to be fired during the negative halfwave of the voltage.

Note: A real triac is fired in positive direction (thyristor1) by a positive gate current and in negative direction (thyristor2) by a negative gate current. The triac goes in blocking condition when the current falls to zero.

This behaviour is simulated by the two firing gates fire1 and fire2:

• fire1=false and fire2=false: gate current = 0, stay in blocking condition
• fire1=true and fire2=false: gate current > 0, fire thyristor1
• fire1=false and fire2=true : gate current < 0, fire thyristor2
• fire1=true and fire2=true : forbidden