YASKAWA U1000 Series Technical Manual page 193

Figure 5.17
Figure 5.17 Time Chart for Speed Search after Recovery from Momentary Power Loss
When performing a speed search operation at start, the speed search operation will start after waiting for the longer of the
times set in b3-05 and L2-03 after the Run command input is received.
When induced voltage remains in the motor, the Speed Search operation starts after the time set in b3-05 without waiting
for the time set in L2-03.
Figure 5.18
Current Detection Speed Search 2 (b3-24 = 2)
■
Current Detection Speed Search 2 is for use with IM motors.
The current set in b3-31 is applied and the speed is detected based on the current flow to the motor. After Speed Search is
completed, the speed is accelerated or decelerated to the frequency reference.
If the output current during the Speed Search operation is larger than the setting value of b3-32, reduce the frequency for
the deceleration time set in b3-03. After motor speed estimation is completed, the speed is accelerated or decelerated to
the frequency reference.
■ Current Detection Speed Search 3 (b3-24 = 4)
The current set in b3-31 is applied and the speed is detected based on the current flow to the motor. After Speed Search is
completed, the speed is accelerated or decelerated to the frequency reference.
If the output current during the Speed Search operation is larger than the setting value of b3-32, reduce the frequency for
the deceleration time set in b3-03. After motor speed estimation is completed, the speed is accelerated or decelerated to
the frequency reference.
b3-14 sets how the drive determines the motor rotation direction when performing the Speed Search as follows:
• The drive uses the frequency reference to determine the direction of motor rotation in order to restart the motor.
• The drive detects the motor rotation direction in order to restart the motor.
Speed Estimation Speed Search (b3-24 = 1)
■
Speed Estimation Speed Search estimates the motor speed while the motor is coasting and then restarts operation. After
the Speed Search is completed, the speed is accelerated or decelerated to the frequency reference.
YASKAWA ELECTRIC SIEP C710636 02B YASKAWA U1000 Technical Manual
AC Power supply
Output frequency
Momentary Power Loss
Minimum Baseblock Time (L2-03)
Run command
Output
frequency
Figure 5.18 Time Chart for Speed Search at Start
b3-05
Momentary Power
Loss
Minimum Baseblock
Time (L2-03)
b3-05
5.2 b: Application
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