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Motor noise, EMI measures
4.20 Motor noise, EMI measures
4.20.1 PWM carrier frequency and Soft-PWM control (Pr. 72, Pr. 240, Pr. 260)
You can change the motor sound.
Parameter
Number
72
PWM frequency selection
*1
240
Soft-PWM operation selection
*1
PWM frequency automatic
260
*2
switchover
*1
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.
*2
Reading and writing are enabled when "0 (SLD) or 1 (LD)" is set in Pr. 570.
(1) 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 EMI measures or on leakage current reduction caused by the PWM switching.
Carrier frequencies under Real sensorless vector control or vector control are as shown below.
200V class (400V class)
FR-A720-02150 (FR-
A740-01100) or less
0 to 5
6 to 9
10 to 13
14, 15
When using an option sine wave filter (MT-BSL/BSC) for the FR-A720-02880 (FR-A740-01440) or more, set "25"
(2.5kHz) in Pr. 72.
REMARKS
When "25" (available with the FR-A720-02880 (FR-A740-01440) or more) is set in Pr. 72, V/F control is forcibly selected.
288
Initial
Name
Value
2
1
1
Pr. 72 Setting
FR-A720-02880 (FR-
A740-01440) or more
0 to 5
6
Setting Range
200V class (400V class)
02150(01100)
0 to 15
or less
02880(01440)
0 to 6, 25
or more
0
1
0
1
Carrier Frequencies (kHz)
2
6
10
14
Description
PWM carrier frequency can be changed.
The setting displayed is in [kHz]. Note
that 0 indicates 0.7kHz, 15 indicates
14.5kHz and 25 indicates 2.5kHz.
Soft-PWM is invalid
"
When Pr. 72 = "0 to 5" (
0 to 4
A720-02880 (FR-A740-01440) or
more), soft-PWM is valid.
PWM carrier frequency is constant
independently of load.
When the carrier frequency is set to
3kHz or more (Pr. 72 "3"), perform
continuous operation at less than 85% of
the rated inverter current.
If the continuous operation is performed
with 85% of the rated current or higher
while the LD is set, the carrier frequency
is lowered to as low as 2kHz.
"
for FR-
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