N5: Feed Forward Control - YASKAWA U1000 Series Technical Manual

• Overexcitation Deceleration can be used in Open and Closed Loop Vector Control, but it lowers the accuracy of Torque
Control, and thereby the braking efficiency. It can be most efficiently used in a V/f Control.
• Overexcitation Deceleration cannot be used with PM motors.
Parameter Adjustments
• When repetitive or long Overexcitation Deceleration results in motor overheat, lower the overexcitation deceleration
gain (n3-13).
• During Overexcitation Deceleration (L3-04 = 4), the drive decelerates at the active deceleration time (C1-02, C1-04,
C1-06, or C1-08). Make sure to set this time so that no overcurrent (oC) fault occurs.
• When a Run command is entered during Overexcitation Deceleration, overexcitation operation is cancelled and the
drive will reaccelerate to the specified speed.
■ n3-13: Overexcitation Deceleration Gain
Multiplies a gain to the V/f pattern output value during Overexcitation Deceleration, thereby determining the level of
overexcitation. The drive returns to the normal V/f value after the motor has stopped or when it is accelerating to the
frequency reference.
No.
n3-13
The optimum setting for n3-13 depends on the motor flux saturation characteristics.
• Increase the gain gradually by 1.25 to 1.90 to improve the braking power of Overexcitation Deceleration.
• If flux saturation characteristics cause overcurrent, try lowering n3-13. A high setting sometimes causes overcurrent
(oC), motor overload (oL1), or overload (oL2).

◆ n5: Feed Forward Control

Enabling Feed Forward can improve the drive's responsiveness to speed reference changes in applications where a high
speed control proportional gain setting (ASR gain, C5-01, C5-03) would lead to problems with overshoot, undershoot, or
oscillation. Figure 5.103
and the function principle are illustrated in
for induction or PM motors (A1-02 = 4 or 7), or in Advanced Open Loop Vector Control for PM motors (A1-02 = 6).
Figure 5.103
Figure 5.104
Frequency
reference after
Feed Forward
Soft Starter
U1-20
YASKAWA ELECTRIC SIEP C710636 02B YASKAWA U1000 Technical Manual
Name
Overexcitation Deceleration Gain
gives an example of overshoot reduction by Feed Forward. Parameters related to this function
Figure 5.104. Feed Forward can only be used in Closed Loop Vector Control
1050
Overshoot
900
750
0
0 0.5 1
Time (s)
Conventional Speed Control
Figure 5.103 Overshoot Suppression by Feed Forward Control
Feed Forward Torque
Compensation Value
Control
n5-02/03
+
Frequency
-
Reference
Speed
Feedback
Figure 5.104 Feed Forward Control
Suppresses
1050
overshoot at the
end of acceleration
900
750
0
0 0.5 1
Time (s)
Feed Forward Control
Feed Forward Control Output
U6-26
+
+
ASR P and I
C5-01/02/03/04
U6-25
Feedback Control Output
5.9 n: Special Adjustments
Setting Range
1.00 to 2.00
ASR Delay and Torque reference
Torque Limits
C5-06, L7-
U1-09
Default
1.10
5
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