TRIAC is composed of two antiparallel thyristors that they have the same gate as indicated by figure below. So you can make a TRIAC in simulink using thyristor blocks easily:)
However the real TRIAC is not exactly equal to the two antiparallel thyristors. For example, not only TRIAC can be turned on by negative current's gate, but also it is recommended to turn it on this way (Because it needs less amount of current's gate this way). Another difference between them is that TRIAC can't tolerate current like thyristor. So in high current cases we use two antiparallel thyristors instead of TRAC.
Be careful in controlling this model. After all you have two thyristors to control and turn on!
Hope it was helpful
