Its possible to have a function say TEACH in controller wich when activated can fire the thyristor at a couple of predermined firing angles and measure the obtained current but is it possilbe to construct a complete look up table from these 2 - 3 values

I would guess that by having a fully calculated and verified table in the "raw" code you could do the following (I demonstrate with 9 values and show 'bottom half' only). I have used this for a different device.

Steps 0, 4 and 8 are measured and the table is then corrected.

table step 0 (min) = 4, measured = 6 (mindiff=2) change to measured 6
table step 1 = 5 change to orig(5) + 3/4 mindiff + 1/4 middiff = 6.75
table step 2 = 6 change to orig(6) + 1/2 mindiff + 1/2 middiff = 7.5
table step 3 = 7 change to orig(7) + 1/4 mindiff + 3/4 middiff = 8.250
table step 4 (mid) = 8, measured = 9 (midddiff = 1) change to measured 9
...

I hope you understand the above, If not, I hope someone does that can explain it better.

This will probably not get you to accurate hit at first fire, but you should be very close.

Erik