User Constant Settings and Functions
5.2.8 Torque Feed-forward Function
5 -42
Principle of Speed Control
Torque reversely proportional to the difference between the speed limit and the speed is fed back to return the
system to within the control speed range when the control speed range is exceeded. The actual motor speed
limit will thus be increased by negative loads.
Motor speed
Speed limit range
V-REF
5.2.8 Torque Feed-forward Function
The torque feed-forward function is used only in control mode except for torque control.
This function shortens positioning time, differentiates a speed reference at the host controller to
generate a torque feed-forward reference,and inputsthisreferencetogether withthe speedrefer-
ence to the Servopack.
Too high a torque feed-forward value will result in overshooting or undershooting. To prevent
this, set the optimum value while observing system response.
Connect a speed reference signal line to V-REF (CN1-5 and 6) and a torque feed-forward refer-
ence signal line to T-REF (CN1-9 and 10).
---
V-REF
Position
reference
Kp
Pn100
Current loop
M
PG
Differ-
ential
K
FF
Speed
calculation
Integration
(Pn101)
+
+
+
+
+
T-REF
Servomotor
Encoder
Host controller
SGDH Servopack
Kp: Position loop gain
K
FF
: Feed-forward gain
+
+
Pn400
Pn300
---
Divider
J
J
Using the Torque Feed-Forward Function
To use the torque feed-forward function, set the following user constant to 2.
Pn002.0
Speed Control Option
(T-REF Terminal Allocation)
Factory
Setting:
0
Speed Control,
Position Control
This setting enables the torque feed-forward function.
Pn002.0 Setting
Description
0
None.
1
T-REF terminal used for external torque limit input.
2
T-REF terminal used for torque feed-forward input.
5
INFO
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