i use sinamics s120 cu320-2pn sensorless vector control to control speed of induction

brake of motor is external controlled from plc . open when you move joystic and close if speed threshold is achieved 

the problem is when motor stop brake is already  active and output torque is still found untill delay time and give (motor block fault f7900)

how can i stop this torque after the brake active?

thank you

Hello,

I presume it is a motor holding brake.

you can control it from the drive also, but you need to make sure that the brake is closed back after the motor speed is 0 and make sure that when you start the motor the brake is already opened.

yes i am sure about the brake(close/ open)

how can the drive know that the brake is closed to stop out put torque immediately?

thank you

Check drive brake parameter you would understand the relation between brake control and toque.

SImple,

the signal to close the brake should be sent when drive speed feedback is 0.

in this case the brake locks the motor in place, you can monitor the speed in r2197 i think.