6.4 Servo Gain Adjustments
6 -27
6.4.3 Making Manual Adjustments
Theautotuningfunctionusesagainadjustmentalgorithmwitha comparativelylarge safetymar-
ginbyconsideringavarietyofmechanicalsystemsto whichthe Servopackisapplied.Therefore,
the Servopack may not satisfy the response characteristicsof some applications. The autotuning
function is not available to machines with low rigidity or high fluctuation.
In such cases, observe the mechanical systems and make manual adjustments of user constants.
J
J
Speed Control
Required User Constants
The following user constants are used.
D
Speed Loop Gain (Pn100)
Thisuserconstantisusedfor determiningthe responsespeed ofthe speedloop. Theresponse
speed increases if the constant is set to a large value provided that the mechanical system
does not vibrate. The value of speed loop gain is the same as the set value of Pn100 if the
inertia ratio set in Pn103 is correct.
Speed loop gain Kv = Set value of Pn100 (Hz)
Set Pn103 to the following value.
Pn103 setvalue
=
Motor axis conversion load inertia (J
L
)
Servomotor rotor inertia (J
M
)
×
100(%)
In the case of manual adjustments of user constants, the user must set the value of user constant Pn103. The
inertia ratio can be obtained if the servo gain constant is written with user constant Fn007 after autotuning has
been performed. For details regarding Fn007, refer to
6.3 Autotuning
.
D
Speed Loop Integral Time Constant (Pn101)
The speed loop has an integral element so that the speed loop can respond to minute inputs.
This integral element delays the operation of the servo system, so a longer positioning set-
ting time is required with slower response speed as the value of the time constant increases.
If the load inertia is large or the mechanical system is likely to vibrate, make sure that the
speed loop integral time constant is large enough; otherwise the mechanical system will vi-
brate. The following formula is the standard.
Ti
2.3
×
1
2
×
Kv
Ti: Integral time constant [s]
Kv: Speed loop gain (calculated from the above) [Hz]
6
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