Gain Adjustment; Current Loop Gain; Speed Loop Gain - Mitsubishi Electric MELDAS MDS-R Series Technical Specification And Instruction Manual

9-2 Gain adjustment

9-2-1 Current loop gain

No. Abbrev. Parameter name
Current loop q axis leading
SV009 IQA
compensation
Current loop d axis leading
SV010 IDA
compensation
SV011 IQG Current loop q axis gain
SV012 IDG Current loop d axis gain

9-2-2 Speed loop gain

(1) Setting the speed loop gain
The speed loop gain (SV005 (VGN1)) is an important parameter for determining the responsiveness
of the servo control. During servo adjustment, the highest extent that this value can be set to becomes
important. The setting value has a large influence on the machine cutting precision and cycle time.
(a) Refer to the following table and set the standard VGN1 according to the size of the entire
load inertia (motor and machine load inertia).
(b) If the standard speed gain setting value is exceeded, the current command fluctuation will
increase even if the speed feedback fluctuates by one pulse. This can cause the machine to
vibrate easily, so set a lower value to increase the machine stability.
Motor unit
250
200
150
Standard
VGN1
100
50
0
100 200
<When machine resonance does not occur at the standard VGN1>
Set the standard VGN1. Use the standard value if no problem (such as machine resonance) occurs. If
sufficient cutting precision cannot be obtained at the standard VGN1, VGN1 can be raised above the
standard value as long as a 70 percent margin in respect to the machine resonance occurrence limit is
maintained. The cutting accuracy can also be improved by adjusting with the disturbance observer.
<When machine resonance occurs at the standard VGN1>
Machine resonance is occurring if the shaft makes abnormal sounds when operating or stopping,
and a fine vibration can be felt when the machine is touched while stopped. Machine resonance
occurs because the servo control responsiveness includes the machine resonance points. (Speed
control resonance points occur, for example, at parts close to the motor such as ball screws.)
Machine resonance can be suppressed by lowering VGN1 and the servo control responsiveness,
but the cutting precision and cycle time are sacrificed. Thus, set a vibration suppression filter and
suppress the machine resonance (Refer to section "9-3-2 Vibration suppression measures"), and
set a value as close as possible to the standard VGN1. If the machine resonance cannot be
sufficiently eliminated even by using a vibration suppression filter, then lower the VGN1.
No. Abbrev. Parameter name
SV005 VGN1

Speed loop gain 1

9. Adjustment
Set the gain of current loop.
As this setting is determined by the motor's electrical
characteristics, the setting is fixed for each type of motor.
Set the standard values for all the parameters depending on each
motor type.
HF74
300 400 500
Load inertia scale (%)
Set the speed loop gain. Set this according to the load inertia size.
The higher the setting value is, the more accurate the control will be,
however, vibration tends to occur. If vibration occurs, adjust by lowering
by 20 to 30%. The value should be determined to be 70 to 80% of the
value at the time when the vibration stops.
Explanation
Motor unit
500
400
HF353
300
200
100
HF44
0
600 100 200
Explanation
9 - 4
Setting range
1 to 20480
1 to 4096
A42
A47
HF203
HF53, 103, 153
300 400 500
Load inertia scale (%)
Setting range
1 to 999
600