Bosch Rexroth OptiFeed-FS EcoDrive 03 FLP04VRS Functional Description page 192

8-46
Functions
Optimize Rejection Filter or
Velocity Loop
Filtering with Two Smoothing
If the step response displays the same behavior, then:
⇒ Check the resonance frequency analysis.
- or -
⇒ Increase the value of CR06, Rejection bandwidth velocity loop by a
much larger amount.
⇒ Using the pre-optimized values for CR05, Rejection frequency
velocity loop and CR06, Rejection bandwidth velocity loop,
optimize the velocity loop again (see above).
The step response defined above must have a similar appearance
with higher values for CR02, Velocity loop proportional gain and/or
smaller values for CR03, Velocity loop integral action time.
⇒ Any additional optimization cycles for CR05, Rejection frequency
velocity loop and CR06, Rejection bandwidth velocity loop must
be based on the step response.
⇒ Using a notch (band suppression) filter for optimization of the control
Filters
loop does not always produce enough improvement in the control
quality. This can happen, for example, when the closed loop has no
salient resonance frequencies. In some situations, activation of a
second smoothing filter (with low pass response) can nevertheless
produce the desired improvement in the control quality.
⇒ To activate this second filter, set parameter CR06, Rejection
bandwidth velocity loop to "-1." The notch filter and the associated
parameter CR05, Rejection frequency velocity loop are deactivated.
Instead of the notch filter, a smoothing filter is activated in the control
loop. This filter has the same smoothing time constant (T
smoothing filter in CR04 Velocity loop smoothing time constant.
Together with the smoothing filter at the velocity loop input, a low pass
filter of the 2nd order (2 poles) is produced. Frequencies greater than
the cut-off frequency (f
and can no longer induce oscillations in the control loop.
The parameter for the filter is set via CR04, Velocity loop smoothing
time constant.
Fig. 8-25: Frequency Response of Low Pass Filters with 1 Pole and with 2 Poles
Note: This setting is made as described in the section entitled:
"Determination of the critical proportional gain and parameter
CR04, Velocity loop smoothing time constant."
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