B3: Speed Search - YASKAWA Z1000U Series Programming Manual

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b3: Speed Search

The Speed Search function allows the drive to detect the speed of a rotating motor shaft that is driven by external forces and
start the motor operation directly from the detected speed without first stopping the machine.
Example: When a momentary loss of power occurs, the drive output shuts off and the motor coasts. When power returns, the
drive can find the speed of the coasting motor and restart it directly.
Enabling Speed Search for PM motors only requires setting parameter b3-01 to 1. The drive offers current detection and speed
estimation Speed Search for induction motors. Parameter b3-24 selects the speed search method for induction motors. Both
methods and relevant parameters are explained below.
Speed Search start timing differs depending on whether operation is after a momentary power loss (L2-01 = 1 or 2) or after
the Speed Search at start (b3-01 = 1). The operation timing of the Speed Search after a momentary power loss is shown in
Figure 1.9. The operation timing after the Speed Search at start is shown in
After restoring power, the Speed Search operation remains in baseblock status for at least the time set in b3-05. However,
Speed Search will not start if the time set in L2-03, Minimum Baseblock Time, does not pass after the power stops. 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 1.9 Timing 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.
n 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. The speed then accelerates or decelerates to the frequency reference after completing
Speed Search. 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.
YASKAWA ELECTRIC SIEP C710636 10C Z1000U HVAC MATRIX Drive Programming Manual
AC Power supply
Output frequency
Minimum Baseblock Time (L2-03)
Run command
Output
frequency
Figure 1.10 Timing Chart for Speed Search at Start
Figure 1.10.
b3-05
Minimum Baseblock
Time (L2-03)
b3-05
1.2 b: Application
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