Question: How can the quickstop function be used when the internal PID controller and a minimum speed is applied?
Answer:
The quickstop (QSP) function ensures that all ramp function generators integrated in the inverter are set to 0 at a separate QSP deceleration ramp. The value falls also below the activated minimum frequency C0239. The QSP function does not act on the PID controller. Therefore, the PID controller continues operating, and due to the missing limitation by C0239 the direction of rotation can reverse.
In case of the Application I/O this behaviour can be stopped by a limitation of the PID controller output via C0230 (min. limit process controller output). A disadvantage is, however, that the motor's speed set value is still 0 and the PID controller is activated. The reason for this behaviour is that the frequency limitation function C0239 the auto DC injection braking is to be deactivated.
This auto DC injection braking function stops and resets the PID controller after the auto DC injection braking time. Moreover, due to the pulse inhibit no voltage is supplied to the motor (without torque).
Please find in the attachment a solution, which avoids all above-mentioned limitations.
