YASKAWA E1000 Technical Manual page 242

5.9 n: Special Adjustments
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Overexcitation Deceleration (Induction Motors)
Overexcitation Deceleration increases the flux during deceleration and allows shorter deceleration time settings without
the use of a braking resistor. Enabled by setting L3-04 to 4 or 5. See
Deceleration on page 223.
Notes on Overexcitation Deceleration
• As regenerative energy is mainly dissipated as heat in the motor, the motor temperature will rise if Overexcitation
Deceleration is applied frequently. In such cases, make sure the motor temperature does not exceed the maximum
allowable value or consider using a braking resistor option instead.
• During Overexcitation Deceleration 2, Hunting Prevention in V/f Control is disabled.
• Do not use Overexcitation Deceleration in combination with a braking resistor option.
• Overexcitation Deceleration can be most efficiently used in a V/f Control.
• Overexcitation Deceleration cannot be used with PM motors.
Parameter Adjustments
• Use parameters n3-13 through n3-23 for adjusting Overexcitation Deceleration.
• When repetitive or long Overexcitation Deceleration results in motor overheat, lower the overexcitation gain (n3-13)
and reduce the overslip suppression current level (n3-21).
• During Overexcitation Deceleration 1 (L3-04 = 4), the drive decelerates at the active deceleration time (C1-02 or
C1-04). Make sure to set this time so that no overvoltage (ov) fault occurs.
• During Overexcitation Deceleration 2 (L3-04 = 5), the drive decelerates using the active deceleration time while
adjusting the deceleration rate in order to keep the DC bus voltage at the level set in L3-17. The actual stopping time
will be longer or shorter than the set deceleration time, depending on the motor characteristics and the load inertia. If
overvoltage occurs (ov), try increasing the deceleration time.
• When a Run command is entered during Overexcitation Deceleration, overexcitation operation is cancelled and the
drive will reaccelerate to the specified speed.
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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 1.30 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 drive overload (oL2). Lowering n3-21 can also help remedy these problems.
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n3-21: High Slip Suppression Current Level
If the motor current exceeds the value set to n3-21 during Overexcitation Deceleration due to flux saturation, the drive
will automatically reduce the overexcitation gain. Parameter n3-21 is set as a percentage of the drive rated current.
This parameter should be set to a relatively low value to optimize deceleration. If overcurrent, oL1, or oL2 occur during
Overexcitation Deceleration, reduce the overslip suppression current level.
No.
n3-21
242
Name
Overexcitation Deceleration Gain
Name
High Slip Suppression Current Level
YASKAWA ELECTRIC SIEP C710616 35D YASKAWA AC Drive E1000 Technical Manual
L3-04: Stall Prevention Selection during
Setting Range
1.00 to 1.40
Setting Range
0 to 150%
Default
1.10
Default
100%