Mitsubishi Electric FR-V500 Instruction Manual page 57

Fine adjustment of gains for speed control
Phenomenon
Speed does not rise to
the speed command.
3
Motor speed is
unstable.
4
Motor or machine hunts
(vibration/noise is
produced).
5
Acceleration/
deceleration time does
not match the setting.
6
Machine operation is
unstable
7
Speed fluctuates at low
speed.
8
Related parameter reference pages
• Pr. 71 "applied motor" (Refer to page 111.)
• Pr. 72 "PWM frequency selection" (Refer to page 112.)
• Pr. 800 "control system selection" (Refer to page 169.)
• Pr. 820 "speed control P gain 1" (Refer to page 175.)
• Pr. 821 "speed control integral time 1" (Refer to page 175.)
• Pr. 822 "speed setting filter 1" (Refer to page 175.)
• Pr. 851 "number of encoder pulses" (Refer to the Instruction Manual (basic).)
• Pr. 854 "excitation ratio" (Refer to page 181.)
• Pr. 902 "speed setting terminal 2 bias" (Refer to page 190.)
• Pr. 903 "speed setting terminal 2 gain" (Refer to page 190.)
• Pr. 917 "terminal 1 bias (speed)" (Refer to page 190.)
• Pr. 918 "terminal 1 gain (speed)" (Refer to page 190.)
Cause
(1) Insufficient torque.
Torque limit is actuated.
(2) Only P (proportional) control is
selected.
(1) The speed command varies.
(2) Insufficient torque.
(3) The speed control gains do not
match the machine.
(mechanical resonance)
(1)The speed control gain is high.
(2) High torque control gain.
(3) Motor wiring and encoder wiring
are not correct.
(1) Insufficient torque.
(2) Large load inertia.
(1) The speed control gains do not
match the machine.
(2) Slow response because of
improper acceleration/
deceleration time of the inverter.
(1) Adverse effect of high carrier
frequency.
(2) Adverse effect of weak excitation.
(3) Low speed control gain.
(1)-1 Increase the torque limit value.
( Refer to the torque limit of speed
control in the Instruction Manual (basic).)
(1)-2 Insufficient capacity
(2) When the load is heavy, speed deviation will
occur under P (proportional) control. Select PI
control.
(1)-1 Check that a correct speed command comes
from the command device. (Take measures
against noises.)
(1)-2 Decrease the PWM carrier frequency in Pr.
72.
(1)-3 Increase the speed setting filter in Pr. 822.
(2)-1 Increase the torque limit value.
( Refer to the torque limit of speed
control in the Instruction Manual (basic).)
(2)-2 Return the excitation ratio in Pr. 854 to the
factory setting (100%).
(3)-1 Perform easy gain tuning.
(3)-2 Adjust Pr. 820 and Pr. 821. (Refer to gain
adjustment.)
(3)-3 Perform speed feed forward control and
model adaptive speed control.
(1)-1 Perform easy gain tuning.
(1)-2 Decrease Pr. 820 and increase Pr. 821.
(1)-3 Perform speed feed forward control and
model adaptive speed control.
(2) Decrease Pr. 824. (Refer to page 53.)
(3) Check wiring.
Check Pr. 852 setting for the encoder rotation
direction.
(1)-1 Increase the torque limit value.
( Refer to the torque limit of speed
control in the Instruction Manual (basic).)
(1)-2 Return the excitation ratio in Pr. 854 to the
factory setting.
(1)-3 Perform speed feed forward control.
(2) Set the acceleration/deceleration time that
meets the load.
(1)-1 Perform easy gain tuning.
(1)-2 Adjust Pr. 820 and Pr. 821. (Refer to page 46.)
(1)-3 Perform speed feed forward control and
model adaptive speed control.
(2) Change the acceleration/deceleration time to
an optimum value.
(1) Decrease the PWM carrier frequency in Pr. 72.
(2) Return the excitation ratio in Pr. 854 to the factory
setting .
(3) Increase Pr. 820 "speed control P gain".
48
Corrective Action