YASKAWA P1000 Technical Manual page 155

<1> After AC power is restored, the drive will wait for at least the time set to b3-05. If the power interruption is longer than
the minimum baseblock time set to L2-03, the drive will wait until the time set to b3-05 has passed after power is restored
before starting Speed Search.
Step 2: Current Injection
Current Injection is performed when there is insufficient residual voltage in the motor after extended power losses, when Speed
Search is applied with the Run command (b3-01 = 1), or when an External search command is used.
This feature injects the amount of DC current set to b3-06 to the motor and detects the speed by measuring the current feedback.
The drive then outputs the detected frequency and increases the voltage using the time constant set to parameter L2-04 while
looking at the motor current.
The output frequency is reduced if the current is higher than the level in b3-02. When the current falls below b3-02, the motor
speed is assumed to be found and the drive starts to accelerate or decelerate to the frequency reference.
Run command
Output
frequency
Output
current
Min. Baseblock Time (L2-03)
<1> The wait time for Speed Search (b3-05) determines the lower limit.
Notes on Using Speed Estimation Speed Search
• Perform Rotational Auto-Tuning for V/f Control (T1-01 = 3) prior to using Speed Estimation in V/f Control and perform
Stationary Auto-Tuning for Line-to-Line Resistance (T1-01 = 2) again if the there is a change in the cable length between
the drive and motor.
• Use Current Detection to search for speeds beyond 200 Hz if the application is running multiple motors from the same drive
or if the motor is considerably smaller than the capacity of the drive.
• Speed Estimation may have trouble finding the actual speed if the motor cable is very long. Use Current Detection in these
instances.
• Use Current Detection instead of Speed Estimation when operating motors smaller than 1.5 kW because Speed Estimation
might not be able to detect the speed or rotation of these smaller motors, in which case Speed Estimation would stop the
motor.
YASKAWA SIEP YAIP1U 01C AC Drive - P1000 Technical Manual
AC power
supply
ON OFF
Output
frequency
Output
current
Min. Baseblock Time
(L2-03)
Figure 5.11 Speed Search after Baseblock
Decelerates at the Speed
Search decel time set to b3-03
ON
OFF
Starts at the speed
speed that was detected
1.0 s
<1>
Figure 5.12 Speed Search at Start
Starts at the speed
that was detected
Several milliseconds
b3 -05 <1>
Waits twice as long as L2-04
b3-02 (Speed search operation current)
5.2 b: Application
Selected
frequency
reference
Frequency reference
set to the drive
5
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