NSK EDD Megatorque Motor - Digital Filter

8. More Advanced Function
— 8-28 —
8.5.2. Digital Filter
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Caution : Use of multi-stage filters may cause the velocity loop to be out of phase,
and it may cause unstable Motor operation.
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Caution : Do not use three or more filters. If the filter frequency is too low, hunting
may occur. It is recommended to set the filter frequency greater than 100
[Hz].
 The digital filter filters the torque command, which is the output of velocity loop. There are two kinds of
filter: the low-pass filter and notch filter.
 Te digital filters are used for reducing in resonant noise and vibration.
Table 8-29: List of digital filter
Name (code)
Function
Initial
setting
Data range
Unit
FP
Primary low-pass filter
0
0: Filter off
10 to 1 000
-
Hz
FS
Secondary low-pass filter
0
0: Filter off
10 to 1 000
-
Hz
NP
Primary notch filter
0
0: Filter off
40 to 1 000
-
Hz
NPQ
Primary notch filter, Q parameter
0.25
0.10 to 5.00
-
NS
Secondary notch filter
0
0: Filter off
40 to 1 000
-
Hz
NSQ
Secondary notch filter, Q parameter
0.25
0.10 to 5.00
-
 Refer to “9. Details of Commands and Parameters” for details of parameters.
 The figure below shows the change in the characteristics of notch filter by the parameters NPQ and NSQ
(Notch filter, primary Q parameter)
 The smaller the notch filter Q is, the wider frequency control is possible, centering around the
frequency set by the notch filter.
Fig 8-12: Characteristics of notch filter
NPQ5.00
NPQ1.00
NPQ0.25
NPQ0.10
NP