Speed Smoothing Control (Pr. 653, Pr. 654) - Mitsubishi Electric FR-F720-00046 Instruction Manual

Motor noise, EMI measures, mechanical resonance
CAUTION
⋅ Decreasing the PWM carrier frequency effect on EMI measures and on leakage current reduction, but increases motor noise.
⋅ When Pr. 570 = "0" (initial value), functions of Pr. 260 become invalid. PWM carrier frequency automatically decreases when load
increases. (Refer to page 81.)
⋅ When PWM carrier frequency is set to 1kHz or less (
operation due to increase in ripple currents, resulting in insufficient torque. In such case, set fast-response current limit
operation invalid using
Pr.156
♦ Parameters referred to ♦
Pr.156 Stall prevention operation selection

4.15.2 Speed smoothing control (Pr. 653, Pr. 654)

Vibration due to mechanical resonance influences the inverter control, causing the output current (torque) to be
unstable. In this case, the output current (torque) fluctuation can be reduced to ease vibration by changing the
output frequency.
Parameter
Name
Number
653
Speed smoothing control
654
Speed smoothing cutoff
frequency
The above parameters can be set when Pr. 160 User group read selection = "0". (Refer to page 179)
...
Specifications differ according to the date assembled. Refer to page 336 to check the SERIAL number.
(1) Control block diagram
Acceleration/deceleration
Speed
command
(2) Setting method
If vibration due to mechanical resonance occurs, set 100% in Pr. 653, run the inverter at the frequency which
generates maximum vibration and check if the vibration will be reduced or not after several seconds.
If effect is not produced, gradually increase the Pr. 653 setting and check the effect repeatedly until the most
effective value is set in Pr. 653.
If vibration becomes large by increasing the Pr. 653 setting, gradually decrease the Pr. 653 setting from 100% to
check the effect in a similar manner.
When the vibrational frequency due to the mechanical resonance (fluctuation of torque, speed, and converter
output voltage) is known using a tester and such, set 1/2 to 1 time of the vibrational frequency to Pr.654. (Setting
vibrational frequency range can suppress the vibration better.)
CAUTION
⋅ Depending on the machine, vibration may not be reduced enough or an effect may not be produced.
160
Pr.72
Stall prevention operation selection.
Refer to page 76
Initial
Value
0
20Hz
processing
Output frequency
+
-
Proportional gain
Cutoff frequency
Current for
torque
Torque fluctuation
detection range
Pr.654
0
≤1), fast-response current limit may function prior to stall prevention
Setting
Range
The torque fluctuation is reduced to reduce vibration due to
0 to 200%
mechanical resonance.
Set the minimum value for the torque variation cycle
0 to 120Hz
(frequency).
V/F control
Speed smoothing control
Cutoff frequency
Pr.654
Pr.653
159Hz (fixed) Vibrational frequency
Description
Frequency output
Voltage output
Current for torque