Troubleshooting In Position Control - Mitsubishi Electric FR-A800 Series Instruction Manual

 Model adaptive position control (Pr.446)
• Set each response for position commands and for load and external disturbances individually.
• Set this parameter when a sufficient position response cannot be obtained after setting Pr.422.
• When setting Pr.446, set Pr.877 = "2" to enable the model adaptive position control, Pr.828 Model speed control gain ≠
"0", and a load inertia ratio in Pr.880 Load inertia ratio.
• Set a small value in Pr.446 first, and then increase the setting gradually and use this parameter within the range where an
overshoot or vibration will not occur.

5.5.12 Troubleshooting in position control

Vector Vector Vector PM PM PM
Condition
The motor does not rotate.
The position is unfavorably
shifted.
Hunting occurs in the motor
or the machine.
Machine movement is
unstable.
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Possible cause
There is incorrect phase sequence
between the motor wiring and encoder
wiring.
The setting of Pr.800 Control method
selection is not appropriate.
No LX signal or STF/STR signal is input. Check if the signals are properly input.
A command pulse or NP signal is not
correctly input.
The setting in Pr.419 Position
command source selection is
incorrect.
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.
search engine
Check the wiring. (Refer to
Check the Pr.800 setting. (Refer to
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 Pr.419 Position command source selection.
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.821 Speed control integral time 1 lower and Pr.821
Speed control integral time 1 higher.
Set Pr.7 Acceleration time, Pr.8 Deceleration time lower.
5.5 Position control under vector control and PM sensorless vector control
Countermeasure
page 87.)
page 221.)
page 226.)
5. PARAMETERS
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