YASKAWA Z1000U Series Programming Manual Download Page 24

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Speed Estimation Speed Search (b3-24 = 1)

A Speed Estimation Speed Search estimates the motor speed while the motor is coasting and then restarts operation. The speed

then accelerates or decelerates to the frequency reference after completing Speed Search.
This method can be used for a single induction motor connected to a drive. Do not use this method if the motor is one or more

frame size smaller than the drive, at motor speeds above 200 Hz, or when using a single drive to operate more than one motor.

Speed Search Activation

Speed Search can be activated using any of the methods 1 through 5 described below. Select the Speed Search type in parameter

b3-24 independent of the activation method.

Method 1.

Automatically activate Speed Search with every Run command. Set b3-01, Speed Search Selection at Start, to 1

(Enabled). External Speed Search commands are ignored.

Method 2.

Activate Speed Search using the digital input terminals.

Use the input functions for H1-

Table 1.7

Table 1.7 Speed Search Activation by Digital Inputs

Setting

Description

b3-24 = 1

b3-24 = 2

External Search

Command 1

Activate Speed Estimation

Speed Search

Closed: Activate Current Detection Speed Search from the

maximum output frequency (E1-04).

External Search

Command 2

Closed: Activate Current Detection Speed Search from the

frequency reference.

To activate Speed Search by a digital input, the input must be set together with the Run command or the Run command must

be entered after giving the Speed Search command.

Method 3.

After automatic fault restart.

When the number of maximum fault restarts in parameter L5-01 is set higher than 0, the drive will automatically perform

Speed Search as specified by b3-24 following a fault.

Method 4.

After momentary power loss.

This mode requires that the Power Loss Ride-Thru function is enabled during CPU operation (L2-01 = 1 or 2).

Refer to L2-01:

Momentary Power Loss Operation Selection on page 109

Method 5.

After external baseblock is released.

The drive will resume the operation starting with Speed Search if the Run command is present and the output frequency is

above the minimum frequency when the Baseblock command (H1-

= 8 or 9) is released.

Rotation Direction Detection Conditions for Backspin

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 direction command.
• 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 direction command.

Refer to b3-50/b3-51: Backspin Search Direction Judgment Time 1/2 on page 28

for details on the backspin direction

judgment time.

Note:

Set b3-50 to the required time to enable rotation direction detection for backspin.

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