Mitsubishi Electric FR-A800 Series Instruction Manual page 263

No. Condition
Motor speed
4
fluctuates.
Hunting (vibration or
acoustic noise)
5
occurs in the motor
or the machine.
Acceleration/
deceleration time is
6
different from the
setting.
Machine movement
7
is unstable.
Rotation ripple
8 occurs during the
low-speed operation.
Parameters referred to
Pr.3 Base frequency, Pr.19 Base frequency
Pr.72 PWM frequency
Pr.80 Motor capacity, Pr.81 Number of motor
Pr.125 Terminal 2 frequency setting gain frequency, Pr.126 Terminal 4 frequency setting gain
Pr.359 Encoder rotation direction, Pr.369 Number of encoder pulses, Pr.851 Control terminal option-Number of encoder pulses, Pr.852 Control terminal
option-Encoder rotation
Pr.822 Speed setting filter
Pr.824 Torque control P gain 1 (current loop proportional
262
5. PARAMETERS
5.3 Speed control under Real sensorless vector control, vector control, PM sensorless vector control
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Possible cause
Speed command varies.
Torque shortage.
Speed control gain is not
suitable for the machine.
(Resonance occurs.)
Speed control gain is too
high.
Torque control gain is
too high.
Motor wiring is incorrect. • Check the wiring.
Torque shortage.
Load inertia is too high.
Speed control gain is not
suitable for the machine.
Response is slow
because of the inverter's
acceleration/
deceleration time
setting.
High carrier frequency is
affecting the motor
rotation.
Speed control gain is too
low.
voltagepage 707
selectionpage 356
polespage 221
directionpage 87
1page 503
search engine
• Check that the speed command sent from the controller is correct. (Take EMC
measures.)
• Set Pr.72 lower.
• Set Pr.822 Speed setting filter 1 higher. (Refer to
• Raise the torque limit.
(Refer to the torque limit for speed control on
• Perform easy gain tuning.
• Adjust Pr.820 Speed control P gain 1 and Pr.821 Speed control integral time
1.
• Perform speed feed forward control or model adaptive speed control.
• Perform easy gain tuning.
• Set Pr.820 lower and Pr.821 higher.
• Perform speed feed forward control or model adaptive speed control.
• Set Pr.824 Torque control P gain 1 (current loop proportional gain) lower.
• Raise the torque limit.
(Refer to the torque limit for speed control on
• Perform speed feed forward control.
• Set acceleration/deceleration time suitable for the load.
• Perform easy gain tuning.
• Adjust Pr.820 and Pr.821.
• Perform speed feed forward control or model adaptive speed control.
• Set the optimum acceleration/deceleration time.
• Set Pr.72 lower.
• Set Pr.820 higher.
gain)page 294
Countermeasure
page 503.)
page 245.)
page 245.)
frequencypage 505