Omron Q2A Series Technical Manual page 787

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Overexcitation Deceleration
Overexcitation deceleration quickly decelerates motors without braking resistors. This lets you stop a motor more
quickly than with the ramp to stop processes.
Overexcitation deceleration increases excitation current during deceleration to cause a large quantity of braking
torque through motor overexcitation. You can set the deceleration speed to adjust the deceleration time for
overexcitation deceleration.
Overexcitation deceleration lets you accelerate the motor again during deceleration.
Enter the Run command during overexcitation deceleration to cancel overexcitation deceleration and accelerate
the drive to the specified speed.
To enable this function, set L3-04 = 1 [StallP@Decel Enable = Enabled]and L3-50 = 3, 4 [StallP@Decel Mode
= HiFlux Overexcitation, HiFlux2 Overexcitation].
When L3-04 = 1 and L3-50 = 3, the motor will decelerate for the deceleration time set in C1-02, C1-04, C1-06, or
C1-08. If the drive detects ov [Overvoltage], increase the deceleration time.
When L3-04 = 1 and L3-50 = 4, the drive uses the value in C1-02, C1-04, C1-06, or C1-08 to decelerate and it
adjusts the deceleration rate to keep the DC bus voltage at the level set in L3-17 [DCBus Regul.Level]. The load
inertia and motor characteristics have an effect on the braking time.
Notes on Overexcitation Deceleration
• Do not use Overexcitation Deceleration with a braking resistor.
• Do not use Overexcitation Deceleration for these applications. Connect a braking resistor to the drive as an
alternative to Overexcitation Deceleration.
– Frequent sudden decelerations
– Continuous regenerative loads
– Low inertia machines
– Machines that have no tolerance for torque ripples
• Motor loss increases during overexcitation deceleration. Use this function when the duty time factor is 5% ED
or less and the braking time is 90 seconds or less. The load inertia and motor characteristics have an effect on
the braking time. You can use overexcitation deceleration in OLV control and CLV control, but those control
methods decrease the precision of torque control and braking efficiency. Use V/f control for the best results.
• The drive disables these functions during braking with Overexcitation Deceleration 2:
– Hunting Prevention Function (V/f Control)
– Torque Limit Speed Control (OLV Control)
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n3-01 HSB Dec Freq Width
No.
Name
(Hex.)
n3-01 HSB Dec Freq Width
(0588)
Expert
When you must detect ov [DC Bus Overvoltage] during high-slip braking, set this parameter to a large value.
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n3-02 HSB CurrLim Level
No.
Name
(Hex.)
n3-02 HSB CurrLim Level
(0589)
Expert
When you decrease the setting value for current suppression, it will make the deceleration time longer.
• When you must detect ov [DC Bus Overvoltage] during high-slip braking, set this parameter to a low value.
• If the motor current increases during high-slip braking, decrease the setting value to prevent burn damage in the
motor.
• The overload tolerance for the drive is 150% for Heavy Duty Rating (HD) and 110% for Normal Duty Rating
(ND).
SIEPYEUOQ2A01A AC Drive Q2A Technical Manual
V/f CL-V/f OLV CLV AOLV
Sets how much the drive lowers the output frequency during high-slip braking as a percentage
where E1-04 [Max Output Frequency] = 100%.
V/f CL-V/f OLV CLV AOLV
Sets the maximum current output during high-slip braking as a percentage where E2-01 [Mot
Rated Current (FLA)] = 100%. Also set the current suppression to prevent exceeding drive
overload tolerance.
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
12.9 n: SPECIAL
Default
(Range)
5%
(1 - 20%)
Default
(Range)
Determined by C6-01, L8-
38
(0 - 200%)
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