bnp-b2365(eng)b.pdf - 第215页

4. Servo Adjustment 4 - 16 (3) Voltage non-sensitive zone (Td) com pensation With the PWM control of the inverter circuit, a dead time (non-energized time) is set to p revent short-circuits caused by simultaneous e nergi…

4. Servo Adjustment

4 - 15

4-3-3 Improving the cutting surface precision

If the cutting surface precision or roundness is poor,

these can be improved by increasing the speed

loop gain (VGN1, VIA) or by using the disturbance

observer function.

• The surface precision in the 45° direction of a

taper or arc is poor.

• The load fluctuation during cutting is large,

causing vibration or surface precision defects

to occur.

POINT

Adjust by raising the speed loop gain equivalently to improve cutting surface

precision, even if the measures differ. In this case, it is important how much the

machine resonance can be controlled, so adjust making sufficient use of

vibration suppression functions.

(1) Adjusting the speed loop gain (VGN1)

If the speed loop gain is increased, the cutting surface precision will be improved but the machine

will resonate easily.

The final VGN1 setting should be approx. 70 to 80% of the maximum value where resonance does

not occur. (Refer to "4-2-2 (1) Setting the speed loop gain")

(2) Adjusting the speed loop leading compensa tion (VIA)

The VIA has a large influence on the position trackability, particularly during high-speed cutting

(generally F1000 or more). Raising the setting value improves the position trackability, and the

contour precision during high-speed cutting can be improved. For high-speed high-precision

cutting machines, adjust so that a value equal to or higher than the standard value can be set.

When VIA is set lower than the standard value and set to a value differing between interpolation

axes, the roundness may worsen (the circle may distort). This is due to differences occurring in the

position trackability between interpolation axes. The distortion can be improved by matching the

VIA with the smaller of the values. Note that because the position trackability is not improved, the

surface precision will not be improved.

(Refer to "4-2-2 (2) Setting the speed loop leading compensation")

No. Abbrev. Parameter name Explanation Setting range

SV005 VGN1 Speed loop gain 1

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.

1 to 999

SV008 VIA Speed loop lead

compensation

Set the gain of the speed loop integration control.

The standard setting is "1364". During the SHG control, the standard

setting is "1900". Adjust the value by increasing/decreasing it by about

100 at a time.

Raise this value to improve contour tracking precision in high-speed

cutting. Lower this value when the position droop vibrates (10 to

20Hz).

1 to 9999

4. Servo Adjustment

4 - 16

(3) Voltage non-sensitive zone (Td) compensation

With the PWM control of the inverter circuit, a dead time (non-energized time) is set to prevent

short-circuits caused by simultaneous energizing of the P side and N side transistors having the

same phase. The dead time has a non-sensitive zone for particularly low voltage commands. Thus,

when feeding with a low speed and a low torque, the control may be unstable.

When an unbalanced axis is lowering, the frictional torque and unbalance torque, and the frictional

torque and deceleration torque before the quadrant changes during circle cutting, are balanced.

The motor output torque will be approximately zero, and the control accuracy may drop. In this

case, the control accuracy can be improved by using the voltage non-sensitive band compensation.

Note that this may cause vibration to be increased while the motor is running.

No. Abbrev. Parameter name Explanation Setting range

SV030 IVC

Voltage dead time

compensation

When 100% is set, the voltage equivalent to the logical non-energized time

will be compensated.

When "0" is set, a 100% compensation will be performed.

Adjust in increments of 10% from the default value 100%.

If increased too much, vibration or vibration noise may be generated.

0 to 200

(%)

Frictional torque

Lowering

Balanced

Unbalance torque

For unbalance torque For circle cutting

Cutting direction

Deceleration torque = frictional torque

Motor torque = 0

4. Servo Adjustment

4 - 17

(4) Disturbance observer

The disturbance observer can reduce the effect caused by disturbance, frictional resistance or

torsion vibration during cutting by estimating the disturbance torque and compensating it. It also is

effective in suppressing the vibration caused by speed leading compensation control.

[1] Set SV082/bit7=1.

[2] Adjust VGN1 to the value where vibration does not occur, and then lower it 10 to 20%.

[3] Set the load inertia scale (SV037: JL) with a percentage in respect to the motor inertia of the

total load inertia.

(Refer to next page for measuring the motor shaft conversion load inertia ratio.)

[4] Set the observer filter band (observer pole) in the disturbance observer filter frequency

(SV043: OBS1), and suppress the high frequency disturbance estimate to suppress the

vibration. Set "100" as a standard.

[5] Set the observer gain in disturbance observer gain (SV044: OBS2). The disturbance observer

will function here for the first time. Set 100 first, and if vibration does not occur, increase the

setting by 50 at a time to increase the observer effect.

No. Abbrev. Parameter name Explanation Setting range

SV037 JL Load inertia scale Set "the motor inertia + motor axis conversion load inertia" in respect to the

motor inertia.

SV037 (JL) =

Jl + Jm

× 100

Jm : Motor inertia

Jl : Motor axis conversion load inertia

0 to 5000

(%)

SV043 OBS1

Disturbance

observer filter

frequency

Set the disturbance observer filter band.

Set to "100" as a standard.

To use the disturbance observer, also set SV037 (JL) and SV044 (OBS2).

When not using, set to "0".

0 to 1000

(rad/s)

SV044 OBS2

Disturbance

observer gain

Set the disturbance observer gain. The standard setting is "100" to "300".

To use the disturbance observer, also set SV037 (JL) and SV043 (OBS1).

When not using, set to "0".

0 to 500

(%)

F EDCBA98765 4 3 2 10

obshj lmc3 lmct

bit Meaning when "0" is set Meaning when "1" is set

obshj

Normal use Disturbance observer

High-load inertia compatible control

SV082

SSF5 Servo function

selection5

POINT

1. The estimated disturbance torque can be output to the D/A output even if the

disturbance observer gain is zero (OBS2 = 0), and the disturbance observer

is not functioning.

2. Sections where the machine is not moving smoothly can be estimated as

the disturbance.

3. The lost motion compensation must be readjusted when the disturbance

observer is started.

4. SV082/bit7 is the characteristics improvement function when load inertia is

large. SV082/bit7 can be set when load inertia is small, also.