B9: Zero Servo - YASKAWA T1000A Technical Manual

No.
b8-17
u b9: Zero Servo
The Zero Servo function is a position loop that can be used in CLV and CLV/PM control modes to lock the motor at a
certain position.
It must be activated using a digital input set for H1-
the motor speed falls below the level set in parameter b2-01, the drive goes into the Zero Servo mode and holds the
current position. When the input assigned to trigger the Zero Servo function is released and the Run command is still
present, the drive reaccelerates.
Figure 5.26
When Zero Servo is active, the deviation between the rotor position and the zero position is displayed in monitor U6-22
(monitor value must be divided by 4 to get the deviation in actual encoder pulses).
A digital output programmed for "Zero Servo complete" (H2-
zero position, plus or minus the Zero Servo completion width set in parameter b9-02.
Note: 1. The Run command must remain on when using the Zero Servo function. If the Run command is switched off, then Zero Servo will no
longer be able to hold the load in place.
2. When the Zero Servo command has shut off, the Zero Servo Completion digital output width also shuts off.
3. Avoid using Zero Servo to lock 100% load for long periods, as this can trigger a fault. If such loads need to be held in place for long
periods, either make sure the current is less than 50% of the drive rated current during Zero Servo, or use a larger capacity drive.
4. If the load rotates the motor when using CLV/PM, a dv4 fault may occur. To prevent this, either increase the Zero Servo gain (b9-01)
or increase the number of pulses set to F1-19 that are required to trigger dv4.
n
b9-01: Zero Servo Gain
Parameter b9-01 adjusts the responsiveness of the Zero Servo position loop. Increase the value if the response is too slow
and the deviation from the zero position rises too high when load is applied. Decrease the value if vibrations occur during
Zero Servo operation.
Note: Before adjusting the Zero Servo gain, make sure the ASR parameters (C5-
not occur when running with a zero speed reference.
No.
b9-01
n
b9-02: Zero Servo Completion Width
Sets the output range of the Zero Servo completion signal. Enter the amount of allowable deviation from the desired
position to trigger Zero Servo. An output terminal set for Zero Servo (H2-
reaches the position Zero Servo position plus or minus b9-02.
No.
b9-02
YASKAWA ELECTRIC SIEP C710616 30B YASKAWA AC Drive T1000A Technical Manual
Name
Energy Saving Parameter (Kt) for PM Motors
Run command
Zero Servo command
Motor Speed
b2-01
DC Injection Braking
start frequency
Figure 5.26 Zero Servo Operation
Name
Zero Servo Gain
Name
Zero Servo Completion Width
= 72. The drive will decelerate when this input is closed. Once
ON
ON
Zero Servo
Operation
= 72) is turned on when the rotor position is within the
) are set up properly and vibration or hunting does
= 33) will be triggered when the motor
5.2 b: Application
Setting Range Default
0.00 to 2.00
OFF
OFF
Setting Range Default
0 to 100
Setting Range Default
0 to 16383
1.00
5
5
10
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