Mitsubishi Electric FR-A700 EC, Instruction Manual, Page: 547 / 826

Parameter Motor noise, noise reduction
FR-A700 EC 6 - 367
6.19 Motor noise, noise reduction
6.19.1 PWM carrier frequency and Soft-PWM control (Pr. 72, Pr. 240, Pr. 260)
You can change the motor sound.
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".
Reading and writing are enabled when "0 (SLD) or 1 (LD)" is set in Pr. 570.
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.
Carrier frequencies under real sensorless vector control or vector control are as shown below.
When using an option sine wave filter (MT-BSL/BSC) for the 02160 or more, set "25" in Pr. 72
(2.5kHz).
Pr.
No.
Name
Initial
Value
Setting Range Description Parameters referred to
Refer to
Section
72
PWM frequency
selection
2
01800
or
less
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
25 ..................... 2.5kHz
156
570
Stall prevention
operation selection
Multiple rating set-
ting 6.7.4
6.7.5
02160
or
more
0–6/25
240
Soft-PWM operation
selection
1
0 Soft-PWM is invalid
1
When Pr. 72 = 0 to 5 (0 to 4 for
01800 or more), Soft-PWM is valid.
260
PWM frequency
automatic
switchover
1
0
PWM carrier frequency is constant
independently of load. When the
carrier frequency is set to 3kHz or
more (Pr. 72
≥
3), perform continu-
ous operation at less than 85% of
the rated inverter current.
1
Decreases PWM carrier frequency
automatically when load increases.
Pr. 72
Carrier Frequencies (kHz)
01800 or less 02160 or more
0 to 5 0 to 5 2
6 to 9 6 6
10 to 3 — 10
14/15 — 14
Tab. 6-101: Carrier frequencies under real sensorless vector control or vector control
NOTE
When "25" (available with the 02160 or more) is set in Pr. 72, V/f control is forcibly selected.