B9: Zero Servo - YASKAWA GA700 Technical Manual

■
b8-51: Standby Mode Wait Time
No.
Name
(Hex.)
b8-51 Standby Mode Wait
Time
(0B01)
◆

b9: Zero Servo

Zero Servo is a position control function that stops and holds the motor shaft. The drive safeties the stopped motor
and an external force will not move the motor.
When you enable the Zero Servo function, the drive will save the home position. The drive can correct the motor
position and put the motor into the home position when the load rotates the motor.
To enable Zero Servo, set H1-xx = 72 [MFDI Function Select = Zero Servo]. The drive starts Zero Servo when
the MFDI terminal set for Zero Servo [H1-xx = 72] activates and the motor speed decreases to less than the value
set in b2-01 [DC Injection/Zero SpeedThreshold]. The drive stops and holds the motor in the Zero Servo start
position. When Zero Servo is enabled, the drive will hold the motor in position when the frequency reference
increases to more than the value set in b2-01. The drive accelerates to the frequency reference when the MFDI
terminal set to trigger the Zero Servo function is released and there is a Run command.
Note:
Zero Servo is available when A1-02 = 3, 7 [Control Method Selection = Closed Loop Vector, PM Closed Loop Vector].
Monitor U6-22 [ZeroServo Pulse Move] shows the difference between the position of the motor shaft and the
Zero Servo start position when Zero Servo is enabled. To find the difference, divide the number of pulses shown
in U6-22 by 4.
When the position of the motor shaft is in the range of "Zero Servo start position ± b9-02 [Zero Servo Completion
Window]", the drive will activate the MFDO set for Zero Servo Complete [H2-xx = 33].
NOTICE: Do not let the Zero Servo function hold 100% load for long periods of time. When the application must use Zero Servo
to hold 100% load for long periods, operate in less than 50% of the drive rated output current or use a larger capacity drive.
Failure to obey will cause damage to the drive.
Note:
• When you use the Zero Servo function, keep the Run command ON. If the Run command is OFF, the drive will not hold the motor
shaft in position.
• When you turn oFF the Zero-Servo command, the terminal set for Zero Servo Complete will deactivate.
• If A1-02 = 7 [PM Closed Loop Vector] and an external force rotates the motor during Zero Servo, the drive will detect dv4 [Inversion
Prevention Detection]. To prevent dv4 detection, increase b9-01 [Zero Servo Gain] or increase the number of pulses set in F1-19
[Deviation 4 Detection Selection].
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b9-01: Zero Servo Gain
No.
Name
(Hex.)
b9-01 Zero Servo Gain
(01DA)
If the drive is not responsive, or if there is too much deviation from the Zero Servo start point when you increase
the load, increase this setting. If oscillation or hunting occurs, decrease this setting.
Note:
• Set C5-xx [Automatic Speed Regulator (ASR)] parameters correctly before you adjust the Zero Servo gain.
• When you operate with the Zero Servo command enabled, oscillation and hunting must not occur.
YASKAWA ELECTRIC SIEP C710617 05F YASKAWA AC Drive GA700 Technical Manual
V/f CL-V/f OLV CLV AOLV
Sets the delay time before turning off the electromagnetic contactor after the
drive stops.
Figure 11.44 Zero Servo Time Chart
V/f CL-V/f OLV CLV AOLV
Sets the responsiveness for the Zero Servo function.
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
11.3 b: Application
Default
(Range)
600 s
(0 - 6000 s)
Default
(Range)
5
(0 - 100)
11
747