Troubleshooting In Position Control - Mitsubishi Electric FR-A820-00046 (0.4K) Instruction Manual

• This function has no effects on servo rigidity at a stop.
• Normally set this parameter to 0.
• When setting Pr.423, set Pr.877 = "0 or 1" to enable position feed forward control.
 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
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.
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.
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.
5.5 Position control under vector control and PM sensorless vector control
Countermeasure
Check the wiring. (Refer to page
Check the Pr.800 setting. (Refer to
Check if the signals are 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 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
220.)
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.
86.)
page 215.)
page
313
5. PARAMETERS
1
2
3
4
5
6
7
8
9
10