The Gto's are triggered as per the following sequence
for conversion process i'll just tell you an easy trick. we have theta=omega*t...so t can be written as theta/omega..
if the angle is 60 degree and frequency is 50 hz..then timeperiod =1/50 and the delay is t= 60/2*3.14*50 ...
Pulse Width : 180/360 =50&
If u hav got any doubts,please contact me..