YASKAWA SGDV SERVOPACK, User Manual

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6.1 Type of Adjustments and Basic Adjustment Procedure
6-9
6
Adjustments
6.1.4
Safety Precautions on Adjustment of Servo Gains
Set the following protective functions of the SERVOPACK to the correct settings before starting to adjust the
servo gains.
(1) Overtravel Function
Set the overtravel function. For details on how to set the overtravel function, refer to 5.2.4 Overtravel .
(2) Force Limit
The force limit calculates the force required to operate the machine and sets the force limits so that the output
force will not be greater than required. Setting force limits can reduce the amount of shock applied to the
machine when troubles occur, such as collisions or interference. If a force limit is set lower than the value that
is needed for operation, overshooting or vibration can be occurred.

For details, refer to 5.8 Limiting Force .
(3) Excessive Position Error Alarm Level
The excessive position error alarm is a protective function that will be enabled when the SERVOPACK is used
in position control.
If this alarm level is set to a suitable value, the SERVOPACK will detect an excessive position error and will
stop the servomotor if the servomotor does not operate according to the reference. The position error indicates
the difference between the position reference value and the actual motor position.

The position error can be calculated from the position loop gain (Pn102) and the motor speed with the follow-
ing equation.
• Excessive Position Error Alarm Level (Pn520 [1 reference unit])

To check the Pn102 setting, change the parameter display setting to display all parameters (Pn00B.0 = 1).
At the end of the equation, a coefficient is shown as
"

(1.2 to 2).
"
This coefficient is used to add a margin that
prevents a position error overflow alarm (A.d00) from occurring in actual operation of the servomotor.
Set the level to a value that satisfies these equations, and no position error overflow alarm (A.d00) will be gen-
erated during normal operation. The servomotor will be stopped, however, if it does not operate according to
the reference and the SERVOPACK detects an excessive position error.
If the acceleration/deceleration of the position reference exceeds the capacity of the servomotor, the servomo-
tor cannot perform at the requested speed, and the allowable level for position error will be increased as not to
satisfy these equations. If so, lower the level of the acceleration/deceleration for the position reference so that
the servomotor can perform at the requested speed or increase the excessive position error alarm level
(Pn520).
CAUTION
• If adjusting the servo gains, observe the following precautions.
• Do not touch the moving section of the servomotor while power is being supplied to the motor.
• Before starting the servomotor, make sure that the SERVOPACK can come to an emergency stop at any time.
• Make sure that a trial operation has been performed without any trouble.
• Install a safety brake on the machine.
Position Error [reference unit] =
× 10
4
Motor Speed [mm/s]
Pn102 [0.1/s]/10
*
Number of Divisions
Linear Scale Pitch [ μ m]/1000
Pn210
Pn20E
× ×
Lin
ear
Pn520
> × × ×
10
4
×
(1.2 to 2)
Max. Motor Speed [mm/s]
Pn102 [0.1/s]/10
*
Number of Divisions
Linear Scale Pitch [
μ m]/1000
Pn210
Pn20E
Lin-
ear