commutation

Hello Community, i want to understand the internals of this circuit which are illustrated in this graph (ignore the red curve), i would like to know how the turn off of the thyristor happens

This part of the schematic from the STSPIN32F0251 EVB allows the user to select between various commutation inputs to operate a BLDC motor in sensored and sensor-less modes. Can anyone help me understand the BEMF measurement part? Also, how is that all the inverting input of the opamps come from...