Simplified model of m
triodes for alternating current, each 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 conditionfire1=true and fire2=false: gate
current > 0, fire thyristor1fire1=false and fire2=true: gate
current < 0, fire thyristor2fire1=true and fire2=true:
forbidden