YASKAWA E-S Series Product Manual page 211

 Torque Reference Filter
As shown in the following diagram, the torque reference filter contains a first order lag filter and
notch filters arranged in series, and each filter operates independently.
The notch filters can be enabled and disabled with the Pn408 = n.X and Pn408 =
n.X.
First stage
Torque reference
first torque
before filter
reference
filter:
Pn401
First order lag filter
 Torque Reference Filter
If you suspect that machine vibration is being caused by the Servo Drive, try adjusting the
torque reference filter time constant. This may stop the vibration. The lower the value, the bet-
ter the control response characteristic will be, but there may be a limit depending on the
machine conditions.
First Stage First Torque Reference Filter Time Constant
Pn401 Setting Range
0 to 65,535
 Notch Filters
The notch filter can eliminate specific frequency elements generated by the vibration of sources
such as resonance of the shaft of a ball screw.
The notch filter puts a notch in the gain curve at the specific vibration frequency (called the
notch frequency). The frequency components near the notch frequency can be reduced or
removed with a notch filter.
Notch filters are set with three parameters for the notch filter frequency, notch filter Q value,
and notch filter depth. This section describes the notch filter Q value and notch filter depth.
• Notch filter Q Value
The setting of the notch filter Q value determines the width of the frequencies that are filtered
for the notch filter frequency. The width of the notch changes with the notch filter Q value. The
larger the notch filter Q value is, the steeper the notch is and the narrower the width of frequen-
cies that are filtered is.
The notch filter frequency characteristics for different notch filter Q values are shown below.
Note: The above notch filter frequency characteristics are based on calculated values and may be different from
actual characteristics.
Torque-Related
Function Selections
Pn408
First stage Second stage
notch
notch
filter: filter
Pn40C
Pn409
Pn40A Pn40D
Pn40E
Pn40B
Notch filter Notch filter
Setting Unit Default Setting
0.01 ms
Q = 1.0
Frequency [Hz]
0
-5
-10
-15
-20
8.8.1 Tuning the Servo Gains
Torque reference
after filter
When Enabled
100 Immediately
Q = 0.7
Q = 0.5
8.8 Manual Tuning
Classification
Tuning
8
8-35