QSP function, automatic activation of the position control for a drift-free standstill

Question:
How does the quick stop function avoid that the drive drifts during standstill?

Answer:
In case of the 9300 servo controller, the 9300 Drive PLC and the ECS servo system the position control loop is activated automatically during quick stop (QSP). If the drive is stopped while the QSP function is activated the speed setpoint is decelerated along the QSP ramp (C0105) and a corresponding position setpoint is formed.
In case of QSP the actual position value for the position control is always derived from the motor encoder (usually the resolver). This is especially the case if e. g. an encoder is connected as second feedback system after the gearbox. As a result, the drive can also be stopped in a controlled way via QSP if the encoder does no longer work reliably because e. g. the contact to the material has been interrupted.

Note:
Even though the speed control mode or torque control mode is set it may be required that for the QSP function the gain of the position controller is set under C0254 . However, normally the default setting should be sufficient.

Behaviour when the current limit is reached:
The actual duration of the QSP ramp is prolonged if the QSP ramp C0105 is set so short that the drive controller has to work at its current limit (Imax, Mmax). The following error occurring in the position control loop in this case is automatically modified internally in such a way that the drive does not reverse after standstill in order to process the following error but remains in standstill. During QSP it is the job of the position control loop to ensure a drift-free standstill.

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