YASKAWA GA700 - Page 715

Parameter Details
11
11.3 b: Application
YASKAWA ELECTRIC SIEP C710617 05F YASKAWA AC Drive GA700 Technical Manual 715
When there is a short baseblock time, the drive searches for residual voltage. The drive uses the residual
voltage in the motor to estimate the motor speed and direction of rotation. The drive outputs the estimated
motor speed as frequency, then uses the deceleration rate set in L2-04 to increase the voltage. When the output
voltage aligns with the V/f pattern, the drive accelerates or decelerates the motor to the frequency reference. If
the drive cannot estimate the motor speed because of low residual voltage, it will automatically do Current
Injection.
Figure 11.31 Speed Search after Baseblock
Note:
After you return power, the drive waits for the time set in b3-05. If power loss is longer than the time set in L2-03, the drive will start
Speed Search when the time set in b3-05 is expired after the power recovery.
2. Current Injection
If there is not sufficient residual voltage in the motor, the drive does Current Injection. The drive injects the
quantity of DC current set in b3-06 [Speed Estimation Current Level 1] into the motor windings to estimate
the motor speed and direction of rotation. The drive outputs the estimated motor speed as frequency, then uses
the deceleration rate set in L2-04 to increase the voltage. When the output voltage aligns with the V/f pattern,
the drive accelerates or decelerates the motor to the frequency reference.
Figure 11.32 Speed Search Selection at Start
Note:
Set the lower limit of the delay time to b3-05 for when Speed Search starts.
■ Speed Search and Operation Conditions
These conditions apply to Speed Search operation. When A1-02 = 0, 1, 2 [Control Method Selection = V/f
Control, V/f Control with Encoder, Open Loop Vector], set b3-24 [Speed Search Method Selection] before you do
Speed Search.
• Do Speed Search with each Run Command
The drive ignores a Speed Search command from the external terminals.
• Use an MFDI to do an External Speed Search Command
To use an MFDI to do Speed Search, input the Run command at the same time that terminal Sx set for Speed
Search activates, or after Speed Search activates.
Set Speed Search to H1-xx to do the function externally. You cannot set external Speed Search 1 and 2 at the
same time.