I wonder if you got the project working?
I´m also doing the same thing but i have another idea for faster response of the brake and less interference in the grid (Thyrsistors can make big noise in the grid).
My plan is as follows:
400VAC => Transformer=>Then i have around 180VAC on sec.side.
180VAC => Full bridge rectifier=>out comes around 220VDC approximately
+220VDC => Connected to one of the brake windings
GND => Goes through N Channel MOSFET drain
MOSFET Source => Goes to other brake winding
Freewheel diode in place between brake windings
The gate of the mosfet will be controlled by MCU (for example arduino) to pulse for the brake signal to go from 0-192VDC.
The Mosfet could also be replaced by IGBT.
Maybe i can manage without the transformer and directly feed the circuit from 230VAC?
What do you think of this, am i missing something important?