CDHD Tuning
User Manual 211
Figur e 9 - 2 1 . I CM D and PE Poor Re su lt
To det ermine whether the oscillations are great er than 300 Hz, use the
ServoStudio FFT function on the PE or I CMD recording:
Figur e 9 - 2 2 . FFT Trace Eva lua t ion
9 .7 Low Pass Filt e r on Curre nt Com m a nd
The output of the HD control loop is a current com m and. This current com m and
is low pass filtered before it is transferred to the current controller.
The Autotuning procedure sets the optim al values for the low pass filter
param eters during the Load Estimation routine.
N LFI LTD AM PI NG (HD Current Filter Dam ping), defined as a percentage,
maintains the bandwidth of the filter up to the cutoff frequency.
N LFI LTT1 (HD Current Filt er Low Pass Rise Time), defined in m illiseconds,
defines the inverse of the cutoff frequency.
I f acoust ical noise occurs, it may be necessary to fine-tune the low pass filter.
I ncrease NLFI LTT1 in increm ental st eps of 10% until the acoust ical noise reaches
an acceptable level.
I f the system becom es unstable, it m ay be necessary to reduce global gain
(KNLUSERGAI N).
After KNLD is tuned, NLFI LTDAMPI NG and/ or NLFI LTT1 can undergo further
tuning. Refer t o KNLD - Derivative Gain
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