YASKAWA U1000 Series Technical Manual page 195

Rotation Direction Detection Conditions for Backspin
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Backspin occurs when the motor rotates in the opposite direction from the rotation direction command.
Specify the speed search direction when power is recovered after a momentary power loss in applications in which
backspin can occur, such as for an oil pump when backspin may occur due to the weight of the oil after a momentary
power loss. The search starts from the rotation direction specified in the direction command when the momentary power
loss time is short.
The search starts from the opposite direction of the direction specified in the direction command when the momentary
power loss time is long. The rotation for the Speed Search is determined as follows:
[t] is the time from the momentary power loss to recovery.
• 0 ≤ t < b3-50: The search is started in the direction specified by the frequency reference.
• b3-50 ≥ t < b3-51: The motor is not restarted and the baseblock continues.
The search starts from the opposite direction of the direction command when the momentary power loss time exceeds
the setting value of b3-51.
• b3-51 ≤ t: The search is started in the direction opposite to the frequency reference.
Refer to b3-50/b3-51 Backspin Search Direction Judgment Time 1/2 on page 198
judgment time.
Note: 1. Set b3-50 to a value higher than 0.0 s to enable rotation direction detection for backspin.
2. When setting b3-50, be sure to also set the following parameters to the values specified. Setting these parameters to any other values
will trigger an oPE08 fault.
b3-50 ≤ b3-51
b3-14 = 0
b3-24 = 2
3. Backspin detection is not necessary with a PM motor and in Closed Loop Vector Control mode.
b3-01: Speed Search Selection at Start
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Determines if Speed Search is automatically performed when a Run command is issued or not.
No.
b3-01
Setting 0: Disabled
When the Run command is entered, the drive starts operating at the minimum output frequency. If external Speed Search
1 or 2 is already enabled by a digital input, the drive will start operating with Speed Search.
Setting 1: Enabled
Speed Search is performed whenever the Run command is entered. The drive begins running the motor once Speed
Search is complete.
b3-03: Speed Search Deceleration Time
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Parameter b3-03 sets the output frequency reduction ramp. The time entered into b3-03 will be the time to decelerate
from maximum frequency (E1-04) to minimum output frequency (E1-09).
In Current Detection Type 2 Speed Search, the time set in this parameter is used as the acceleration or deceleration time
for the output frequency while searching.
No.
b3-03
b3-04: V/f Gain during Speed Search (Speed Estimation Type)
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During Speed Search, the output voltage calculated from the V/f pattern is multiplied with this value. Changing this
parameter can help reduce the output current during Speed Search.
No.
b3-04
YASKAWA ELECTRIC SIEP C710636 02B YASKAWA U1000 Technical Manual
Parameter Name
Speed Search Selection at Start
Name
Speed Search Deceleration Time
Name
V/f Gain during Speed Search (Speed Estimation Type)
5.2 b: Application
for details on the backspin direction
Setting Range Default
0 or 1 Determined by A1-02
Setting Range Default
0.1 to 10.0 s
Setting Range Default
Determined by C6-01 and
10 to 100%
5
2.0 s
o2-04
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