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Motor noise, noise reduction
4.20 Motor noise, noise reduction
4.20.1 PWM carrier frequency and Soft-PWM control (Pr. 72, Pr. 240, Pr. 260)
(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 reducing noise or leakage current generated from the inverter.
⋅ Carrier frequencies under real sensorless vector control or vector control are as shown below.
You can change the motor sound.
Parameter
Number
Name
Initial
Value
Setting Range Description
72 *1 PWM frequency selection 2
01800 or less 0 to 15 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.
02160 or
more
0 to 6, 25
240
*1 Soft-PWM operation selection 1
0 Soft-PWM is invalid
1
When Pr. 72 = "0 to 5" (
"0 to 4" for 02160
or more), soft-PWM is valid.
260
*2
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
continuous operation at less than 85% of
the rated inverter current.
1
Decreases PWM carrier frequency
automatically when load increases.
*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.
Pr. 72 Setting
Carrier Frequencies (kHz)
01800 or less 02160 or more
0 to 5 0 to 5 2
6 to 9 6 6
10 to 13 ⎯ 10
14, 15 ⎯ 14
⋅ When using an option sine wave filter (MT-BSL/BSC) for the 02160 or more, set "25" in Pr. 72 (2.5kHz).
REMARKS
When "25" (available with the 02160 or more) is set in Pr. 72, V/F control is forcibly selected.
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