bnp-b2365(eng)b.pdf - 第219页
4. Servo Adjustment 4 - 20 (2) Acceleration feed fo rward Vibration may occur at 10 to 20 Hz during accelera tion/deceleratio n when a short time consta nt of 30 ms or less is applied, and a positio n loop gai n (PGN1) h…
4. Servo Adjustment
4 - 19
4-3-4 Improvement of characteristics during acceleration/deceleration
(1) SHG control (option function)
Because SHG control has a smoother response during acceleration/deceleration than
conventional position controls, the acceleration/deceleration torque (current FB) has more ideal
output characteristics (A constant torque is output during acceleration/deceleration.) The peak
torque is kept low by the same acceleration/deceleration time constant, enabling the time constant
to be shortened.
Refer to item "(3) SHG control" in section "4-2-3 Position loop gain" for details on setting SHG
control.
No. Abbrev. Parameter name Setting ratio Setting example Explanation Setting range
SV003
(SV049)
PGN1
(PGN1sp)
Position loop gain 1 1 23 26 33 38 47 1 to 200
SV004
(SV050)
PGN2
(PGN2sp)
Position loop gain 2
8
3
62 70 86 102 125 0 to 999
SV057
(SV058)
SHGC
(SHGCsp)
SHG control gain 6 140 160 187 225 281
Always set with a
combination of
these three
parameters.
0 to 1200
SV008 VIA
Speed loop lead
compensation
Set 1900 as a standard value during SHG control. 1 to 9999
SV015 FFC
Acceleration rate
feed forward gain
Set 100 as a standard value during SHG control. 0 to 999
POINT
SHG control is an option function. If the option is not set in the NC, alarm 37 (at
power ON), or warning E4 and error parameter No. 104 (2304 for M60S/E60
Series NC) will be output.
0
0
3000
200
-200
-3000
0
0
3000
200
-200
-3000
Acceleration/deceleration characteristics during conventional control
Speed command
(r/min)
Current FB
(stall current%)
Time
Time
Acceleration/deceleration characteristics during SHG control
Speed command
(r/min)
Current FB
(stall current %)
Time
Time
4. Servo Adjustment
4 - 20
(2) Acceleration feed forward
Vibration may occur at 10 to 20 Hz during acceleration/deceleration when a short time constant of
30 ms or less is applied, and a position loop gain (PGN1) higher than the general standard value or
SHG control is used. This is because the torque is insufficient when starting or when starting
deceleration, and can be resolved by setting the acceleration rate feed forward gain (SV015: FFC).
This is also effective in reducing the peak current (torque).
While measuring the current command waveform, increase FFC by 50 to 100 at a time and set the
value where vibration does not occur.
No FFC setting With FFC setting
Acceleration rate feed forward gain means that the speed loop gain during
acceleration/deceleration is raised equivalently. Thus, the torque (current command) required
during acceleration/deceleration starts sooner. The synchronization precision will improve if the
FFC of the delayed side axis is raised between axes for which high-precision synchronous control
(such as synchronous tapping control and superimposition control).
No. Abbrev. Parameter name Explanation Setting range
SV015 FFC Acceleration rate
feed forward gain
When a relative error in the synchronous control is large, apply this
parameter to the axis that is delaying. The standard setting value is "0". For
the SHG control, set to "100".
To adjust a relative error in acceleration/deceleration, increase the value
by 50 to 100 at a time.
0 to 999
(%)
POINT
Overshooting occurs easily when a value above the standard value is set during
SHG control.
Current
command
(%)
200
100
0
100
806040
20 0
Time (ms)
200
100
0
100
8060 40
200
Time (ms)
4. Servo Adjustment
4 - 21
(3) Inductive voltage compensation
The current loop response is improved by compensating the back electromotive force element
induced by the motor rotation. This improved the current command efficiency, and allows the
acceleration/deceleration time constant to the shortened.
<Adjustment method>
1. While accelerating/decelerating at rapid traverse, adjust the inductive voltage compensation
gain (SV047: EC) so that the current FB peak is a few % smaller than the current command
peak.
Inductive voltage compensation
No. Abbrev. Parameter name Explanation Setting range
SV047 EC Inductive voltage
compensation gain
Set the inductive voltage compensation gain. Set to "100" as a standard.
If the current FB peak exceeds the current command peak, lower the gain.
0 to 200
(%)
POINT
If the current FB peak becomes larger than the current command peak (over
compensation), an overcurrent (alarm 3A) will occur easily. Note that over
compensation will occur easily if the load inertia is large.
0
0
3000
200
-200
-3000
Speed command
(r/min)
Current
command
(Rated current %)
No inductive voltage
compensation
With inductive
voltage
compensation
Time
Time