*
M’Ax User Guide
93
Issue Number: 4
Procedure
1.
Make the signal connections shown in Figure D-1. Make the
SPEED
REFERENCE
connections for either high or standard precision as
appropriate, not both. Connect an oscilloscope to terminal 11
(
SPEED
) and terminal 9 (
CURRENT
) of the
SIM ENC
connector.
2.
Ensure the
Hardware enable
contact is open or that parameter
6.15
Drive enable is set at
0
.
3.
Connect the AC supply to the Drive.
4.
Set
2.02
{
0.24
} Ramp enable at
0
.
5.
Ensure
3.16
{
0.12
} Speed-loop gains selector is set at
1
in order to
select PID-gains set 1 in the Drive and PID-buffer 1 in the
SLM
. (If a
different PID-gains set is to be adjusted, set
3.16
{
0.12
} accordingly;
see Gain sequencing later in this chapter.)
6.
Connect the load to the motor.
7.
Set
11.64
{
0.17
} SLM online enable at
1
. This allows the
SLM
to be
updated with new values of the PID-gains parameters.
Following power-up, new PID-gain(s) value(s) take
effect only after the motor shaft has passed through the
zero position of the feedback encoder.
8.
Close the
Hardware enable
contact or set parameter
6.15
Drive
enable at
1
.
9.
Set the motor running at a suitable speed, then stop and re-start the
Drive as required.
10. To increase the speed of response to a change in speed demand, or
to a change in load, increase
3.10
{
0.13
} Speed-loop proportional
gain.
Set
3.10
{
0.13
} just below the value that causes the motor to vibrate.
It is common for the vibration to be worse at zero speed. An
excessive proportional gain can result in instability.
11. To improve the ability of the Drive to maintain a speed demand
under steady-state or slowly-changing conditions, increase
3.11
{
0.14
} Speed-loop integral gain.
A high value of
3.11
{
0.14
} can cause the motor speed to vary
sinusoidally around the speed demand. This effect can be minimized
by increasing the value of
3.10
{
0.13
} Speed-loop proportional gain.
12. To reduce overshoot when the speed demand or the load on the
motor is suddenly changed, increase
3.12
{
0.15
} Speed-loop
derivative gain. Excessive derivative gain will cause noise in the
motor.
13. If mechanical resonances are affecting the performance of the
system, reduce the value of
4.12
{
0.16
} Current-demand filter 1 cut-
off frequency, then repeat steps 10 to 12. Repeat this step as
required.
14. Set
11.64
{
0.17
} SLM online enable at
0
to prevent inadvertent
adjustments. Do
not
leave this parameter set at
1
.
15. Perform the following, as appropriate:
Version _AN
Initiate the save operation by setting parameter
XX.00
at
1000
.
Execute the operation by performing either of the following:
•
While the display is in Edit mode, press at the same time:
•
Set parameter 10.38 at 100 (via serial communications)
Version _SL
Version _AN
(if required)
Ensure the Drive is disabled by checking that the
Hardware enable
contact is open or that parameter
6.15
is set at
0
, then perform either
of the following:
•
Initiate the store operation by setting parameter
0.50
at
2
(
Prog
).
Execute the operation by setting parameter
10.38
at
100
.
•
Set
11.67
Flash update enable at
1
.
16. To use the saved values (version _
AN
only) after the next power-up,
ensure parameter
0.50
is set at
no
(
0
). If you have to change the
setting, immediately afterwards execute the operation, as described
in step 15.
17. To use the stored values after the next power-up, ensure parameter
0.50
is set at
4
(
boot2
). If you have to change the setting,
immediately afterwards execute the operation, as described in step
15.
18. Disconnect the AC supply.
19. Re-make the required signal connections for the application.
Figure D-2
Response to a step-change in speed demand when the
speed-loop PID gains are adjusted
The waveforms shown in Figure D-2 represent the
SPEED
output signal
from terminal 11 of the
SIM ENC
signal connector when the speed
demand is a square-wave.
D.3
Specifying shaft stiffness and load
inertia
When the following are entered into the appropriate parameters, the
Drive can calculate the required PID gains:
•
Stiffness angle
•
Load inertia
Stiffness angle
Stiffness angle is defined as the angular displacement of the motor shaft
that would cause the Drive to deliver a torque-producing current
equivalent to the value of FLC (without field weakening). Smaller
stiffness angles result in the following:
•
Greater shaft stiffness
•
Greater peak currents with increased possibility of the Drive tripping
on over-current
•
Smaller stability margin
Typical values are 6 to 10°.
Load inertia
Load inertia should include the inertia of the following, as appropriate:
•
Shaft(s)
•
Attachments (e.g. brake)
•
Gearing
If gearing is employed, the value of reflected load inertia must be used.
The Drive can accept inertia values in either kgm
2
or kgcm
2
(indicated by
5.34
Inertia units selected, which is set by the motor manufacturer).
If required, see also Gain sequencing on page 96.
No special signal connections are required.
CAUTION
and
Speed demand
Insufficient proportional
gain [0.13]
Excessive proportional
gain [0.13]
Excessive integral gain
[0.14]
Ideal response
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