Mitsubishi FR-A740-00023-EC, Instruction Manual

Page: 115 / 474

105
Speed control by real sensorless vector
control, vector control
4
P
ARAME
T
E
R
S
4 Motor speed is unstable.
(1) The speed command varies. (1) -1 Check that a correct speed command comes from
the command device. (Take measures against
noises.)
(1) -2 Decrease Pr. 72 PWM frequency selection .
(1) -3 Increase Pr. 822 Speed setting filter 1 . (Refer to page
280 )
(2) Insufficient torque. (2) Increase the torque limit value.
(Refer to torque limit of speed control on page 94 )
(3) The speed control gains do not
match the machine. (mechanical
resonance)
(3) -1 Perform easy gain tuning.
(Refer to page 100 )
(3) -2 Adjust Pr. 820, Pr. 821 . (Refer to page 102)
(3) -3 Perform speed feed forward/model adaptive speed
control.
5
Motor or machine hunts
(vibration/noise is
produced).
(1) The speed control gain is high. (1) -1 Perform easy gain tuning. (Refer to page 100)
(1) -2 Decrease Pr. 820 and increase Pr. 821 .
(1) -3 Perform speed feed foward control and model
adaptive speed control.
(2) The torque control gain is high. (2) Decrease the Pr. 824 value. (Refer to page 122 )
(3) The motor wiring is wrong. (3) Check the wiring
6
Acceleration/deceleration
time does not match the
setting.
(1) Insufficient torque. (1) -1 Increase the torque limit value.
(Refer to torque limit of speed control on page 94 )
(1) -2 Perform speed feed foward control.
(2) Large load inertia. (2) Set the acceleration/deceleration time that meets the
load.
7
Machine operation is
unstable
(1) The speed control gains do not
match the machine.
(1) -1 Perform easy gain tuning. (Refer to page 100)
(1) -2 Adjust
Pr. 820, Pr. 821
.
(Refer to page 102)
(1) -3 Perform speed feed foward control and model
adaptive speed control.
(2) Slow response because of
improper acceleration/
deceleration time of the inverter.
(2) Change the acceleration/deceleration time to an
optimum value.
8
Speed fluctuates at low
speed.
(1) Adverse effect of high carrier
frequency.
(1) Decrease Pr. 72 PWM frequency selection .
(2) Low speed control gain. (2) Increase
Pr. 820 Speed control P gain 1
.
Phenomenon Cause Countermeasures