Speed Smoothing Control - Mitsubishi Electric 800 Series Instruction Manual

15.12

Speed smoothing control

V/F V/F Magnetic flux V/F Magnetic flux Magnetic flux
The output current (torque) of the inverter sometimes becomes unstable due to vibration caused by mechanical resonance.
Such vibration can be suppressed by reducing fluctuation of the output current (torque) by changing the output frequency.
Pr. Name
653 Speed smoothing
G410 control
654 Speed smoothing
G411 cutoff frequency
 Control block diagram
Acceleration/deceleration
processing
Speed
command
 Setting method
• When vibration caused by mechanical resonance occurs, set 100% in Pr.653 Speed smoothing control, perform
operation at the frequency with the largest vibration, and check if the vibration is suppressed after few seconds.
• If the setting is not effective, gradually increase the value set in Pr.653 and repeat the operation to check the effect to
determine the most effective value (Pr.653).
• If the vibration increases by increasing the value in Pr.653, decrease the value in Pr.653 from 100% to check the effect.
• When the vibrational frequency at which mechanical resonance occurs (during fluctuation of torque, speed, or converter
output voltage) is measured using an instrument such as a tester, set 1/2 to 1 times of the vibrational frequency in Pr.654
Speed smoothing cutoff frequency. (Setting the resonance frequency range mitigates vibration more effectively.)
Cutoff frequency
Current for
torque
Torque fluctuation
detection range
0
Pr.654
NOTE
• Depending on the equipment, the vibration may not be suppressed sufficiently or the setting is not effective.
Setting
Initial value
range
0% 0% to 200%
20 Hz 0 to 120 Hz
Output frequency
+
V/F control
-
Speed smoothing control
Cutoff frequency
Pr.654
Proportional gain
Pr.653
159Hz (fixed) Vibrational frequency
Description
Check the effect by increasing and decreasing the value at around
100%.
Set the minimum frequency for the torque variation cycle.
Frequency output
Voltage output
Current for torque
15. (G) Control Parameters
15.12 Speed smoothing control
11
12
13
14
15
16
17
18
19
20
395