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Operation selection function
2.10.2 PWM carrier frequency (Pr. 70 , Pr. 72 )
<Setting>
• By parameter setting, you can set whether to exercise Soft-PWM control that
changes the motor tone or select with or without long wiring mode.
• Soft-PWM control is a control method that changes the motor noise from a metallic
tone into an unoffending complex tone.
• Surge voltage is suppressed regardless of wiring length in the long wiring mode. (When
operating the 400V motor with wiring length of 40m or longer, select the long wiring mode.)
Refer to (page 80).
You can change the motor sound.
Parameter Name
Factory
Setting
Setting
Range
Remarks
70 Soft-PWM setting 11 0, 1, 10, 11
Setting is enabled when
Pr. 30 = "1"
72 PWM frequency selection 1 0 to 15
Pr.70
Setting
Description
Soft-PWM Long wiring mode Remarks
0 Invalid Invalid
1
Valid
(When Pr. 72 setting
= any of "0" to "5")
Invalid
10 Invalid Valid
•When Pr. 72 "PWM frequency
selection" = 1 or more, the PWM
carrier frequency is constant at
1kHz. (When "0" is set, the PWM
carrier frequency is constant at
0.7kHz.)
11 Valid Valid
CAUTION
1.When "10 or 11" is set in Pr. 70, the output voltage at rated frequency drops 5V
maximum.
2.For the 400V class, use an insulation-enhanced motor.
Refer to page 24 for an inverter-driven 400V class motor.
Pr. 72 Setting Description
0 to 15
PWM carrier frequency can be changed.
The setting displayed is in [kHz].
Note that 0 indicates 0.7kHz and 15 indicates 14.5kHz.
REMARKS
•An increased PWM frequency will decrease the motor sound but increase noise and leakage
currents. Therefore, perform the reduction techniques. (Refer to page 17.)
•Metallic sound may be generated from the motor at sudden deceleration but it is not a fault.
•If low acoustic noise operation is performed at higher PWM frequency, performing continuous
operation at 75% or more of the rated current may increase motor noise, but it is not a failure.