Yaskawa F7 Drive Programming Manual - Manual (Page 22)

Programming 14
b3 Speed Search
The Speed Search function allows the Drive to determine the speed of a motor shaft that is being driven by rotational inertia. Speed
Search will allow the Drive to determine the speed of the already rotating motor and begin to ramp the motor to a set speed without
first having to bring it to a complete stop. When a momentary loss of supply power is experienced, the Drive output is turned off.
This results in a coasting motor. When power returns, the Drive can determine the speed of the coasting motor and start without
requiring it to be brought to minimum speed. Speed Search can be programmed to always be active by setting b3-01 or it can be
commanded by remote contact closure by setting a digital input.
There are two forms of Speed Search in the Drive, the speed estimation method and the current detection method.
Parameters L2-03 and L2-04 also affect the current detection method of Speed Search operation.
b3-01 Speed Search Selection
Speed Estimation: Method (b3-01= 0 or 1) The speed estimation method will calculate the speed using measurements of
residual motor fields. The speed estimation version is bi-directional and will determine both the motor speed and direction. To
enable speed estimation Speed Search at start, set b3-01= “1: SpdsrchF Enable”.
.
IMPORTANT
When setting the Drive for remote Speed Search input, via a contact closure, the method of Speed Search
is determined by the setting of b3-01. If b3-01= ”0: SpdsrchF Disable” then the remote input will initiate
speed estimation method, and if b3-01= ”2: SpdsrchI Disable”, then the remote input will start the current
detection method.
Setting Description
0 Speed Estimation Speed Search Disable
1 Speed Estimation Speed Search Enable
2 Current Detection Speed Search Disable (factory default)
3 Current Detection Speed Search Enable
IMPORTANT
If the speed estimation method of Speed Search is to be used, then Auto-tuning must be performed prior to
using Speed Search. If the length of cable between the Drive and motor is ever changed after Auto-tuning
then Auto-tuning should be performed again.
IMPORTANT
The speed estimation mode cannot be used when there are multiple motors operated by one Drive or the
motor is two or more frames smaller than the standard size motor per the Drive capacity.