Mitsubishi Electric FR-D720S SC EC, Instruction Manual

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Motor noise, EMI measures, mechanical resonance Parameter
6 - 144
6.14 Motor noise, EMI measures, mechanical resonance
6.14.1 PWM carrier frequency and soft-PWM control (Pr. 72, Pr. 240, Pr. 260)
You can change the motor sound.
The above parameters can be set when Pr. 160 = 0.
The above parameters allow its setting to be changed during operation in any operation
mode even if "0" (initial value) is set in Pr. 77 "Parameter write selection".
PWM carrier frequency changing (Pr. 72)
You can change the PWM carrier frequency of the inverter.
Changing the PWM carrier frequency produces an effect on avoiding the resonance frequency
of a mechanical system or motor or on reducing noise or leakage current generated from the
inverter.
Soft-PWM control (Pr. 240)
Soft-PWM control is a control system that changes the motor noise from a metallic tone into
an unoffending complex tone.
Purpose Parameters that must be set
Refer to
Section
Reduction of the motor noise
Measures against EMI and leakage
currents Carrier frequency and Soft-PWM selection Pr. 72, Pr. 240,
Pr. 260 6.14.1
Reduce mechanical resonance Speed smoothing control Pr. 653 6.14.2
Pr.
No.
Name
Initial
Value
Setting Range Description Parameters referred to
Refer to
Section
72
PWM frequency
selection
1
0–15
(integral value)
PWM carrier frequency can be
changed. The setting displayed is in
[kHz]. The settings indicate the fol-
lowing frequencies:
0 .............. 0.7kHz
Settings between 1–14 correspond
directly to the frequency values.
15 .......... 14.5kHz
156 Stall prevention
operation selec-
tion 6.2.4
240
Soft-PWM operation
selection
1
0 Soft-PWM is invalid
1
When Pr. 72 = 0 to 5, Soft-PWM is
valid.
260
PWM frequency
automatic switchover
0
0
PWM carrier frequency is constant
independently of load.
1
Decreases PWM carrier frequency
automatically when load increases.