Mitsubishi Electric FR-A700 Technical Manual page 263

Case
(1) The speed command varies.
Motor speed is
4 (2) Insufficient torque.
unstable.
(3) The speed control gains do not match the
machine. (Machine resonances.)
(1) The speed control gain is high.
Motor or machine
hunts (vibration/
5
noise is
produced). (2) The torque control gain is high.
(3) The motor wiring is wrong
(1) Insufficient torque.
Acceleration/
deceleration time
6
does not match
(2) Large load inertia.
the setting.
(1) The speed control gains do not match the
machine.
Machine operation
7
is unstable.
(2) Slow response because of improper
acceleration/deceleration time of the inverter.
Speed fluctuation (1) Adverse effect of high carrier frequency.
8
at low speed. (2) Low speed control gain.
Cause
(1)-1
(1)-2
(1)-3
(2) Increase the torque limit value.
(3)-1
(3)-2
(3)-3
(1)-1
(1)-2
(1)-3
(2) Decrease the [Pr. 824] value.
(3) Check the wiring
(1)-1
(1)-2
(2) Set the acceleration/deceleration time that meets the
(1)-1
(1)-2
(1)-3
(2) Change the acceleration/deceleration time to an
(1) Decrease [Pr. 72 PWM frequency selection].
(2) Increase [Pr. 820 Speed control P gain 1].
297
Countermeasures
Check that a correct speed command comes from the
command device. (Take measures against noises.)
Decrease [Pr. 72 PWM frequency selection] .
Increase [Pr. 822 Speed setting filter 1] .
(Refer to page 323)
(Refer to torque limit of speed control on page 283)
Perform easy gain tuning.
Adjust [Pr. 820, 821].
Perform speed feed forward/model adaptive speed
control.
Perform easy gain tuning.
Decrease [Pr. 820] and increase [Pr. 821] .
Perform speed feed forward control and model
adaptive speed control.
Increase the torque limit value.
(Refer to torque limit of speed control on page
Perform speed feed forward control.
load.
Perform easy gain tuning.
Adjust [Pr. 820, 821] .
Perform speed feed forward control and model
adaptive speed control.
optimum value.
PARAMETER
283
)
2