Troubleshooting In Position Control - Mitsubishi Electric 800 Series Instruction Manual

5.5.11

Troubleshooting in position control

Condition
1 The motor does not rotate.
The position is unfavorably
2
shifted.
Hunting occurs in the motor
3
or the machine.
Machine movement is
4
unstable.
Cause
There is incorrect phase sequence
between the motor wiring and
encoder wiring.
Control mode selection setting Pr.800
Control method selection is not
appropriate.
No servo ON or stroke end signals
(STF/STR) are input.
A command pulse or position pulse
sign (NP) is not correctly input.
The setting in Pr.419 Position
command source selection
(position command source selection)
is not correct.
When simple position control by a
point table (Pr.419= "0") is used , the
position feed length set by Pr.465 to
Pr.494 is not correct.
The option to be used and parameter
settings do not match.
A command pulse is not correctly
input.
The command is affected by noise.
Noise is superpositioned on the
encoder feedback signals.
Position loop gain is too high.
Speed loop gain is too high.
Acceleration/deceleration time
settings are affecting adversely.
Position control under vector control
Countermeasure
Check the wiring. (Refer to page
Check the Pr.800 setting. (Refer to
Check if a signal is properly input.
Check if the command pulse is properly input (check the
accumulated value for command pulses in Pr.430 Pulse
monitor selection).
Check the command pulse type in Pr.428 Command pulse
selection.
Check that the position pulse sign (NP) is assigned to an input
terminal. (inverter pulse input)
Check the position command source selection in Pr.419.
Check the position feed length in Pr.465 to Pr.494.
Correctly set Pr.862 Encoder option selection according to
the option to be used. (Refer to
Check the command pulse type in Pr.428 Command pulse
selection.
Check if the command pulse is properly input (check the
accumulated value of command pulses in Pr.430).
Check that the position pulse sign (NP) is assigned to an input
terminal. (inverter pulse input)
Set Pr.72 PWM frequency selection lower.
Change the earthing (grounding) position of the shielded
cable. Alternatively, do not connect it.
Set Pr.422 Position control gain lower.
Perform easy gain tuning.
Set Pr.820 Speed control P gain 1 lower and Pr.821 Speed
control integral time 1 higher.
Set Pr.7 Acceleration time and Pr.8 Deceleration time
lower.
PARAMETERS
Vector Vector Vector
60.)
page 137.)
page 141.)
237
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