5.9 n: Special Adjustments
YASKAWA ELECTRIC
SIEP C710636 02B YASKAWA U1000 Technical Manual
323
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• 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.
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.
gives an example of overshoot reduction by Feed Forward. Parameters related to this function
and the function principle are illustrated in
. Feed Forward can only be used in Closed Loop Vector Control
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 5.103 Overshoot Suppression by Feed Forward Control
Figure 5.104
Figure 5.104 Feed Forward Control
No.
Name
Setting Range
Default
n3-13
Overexcitation Deceleration Gain
1.00 to 2.00
1.10
1050
Overshoot
Conventional Speed Control
Feed Forward Control
Time (s)
Motor Speed (min
-1
)
Motor Speed (min
-1
)
Time (s)
900
750
0
1050
900
750
0
0
0.5
1
0
0.5
1
Suppresses
overshoot at the
end of acceleration
ASR P and I
C5-01/02/03/04
Feed Forward
Control
n5-02/03
Frequency
reference after
Soft Starter
ASR Delay and
Torque Limits
C5-06, L7-
+
+
+
-
Speed
Feedback
U6-26
U6-25
U1-20
Feed Forward Control Output
Feedback Control Output
U1-09
Frequency
Reference
Feed Forward Torque
Compensation Value
Torque reference
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