4.16 Motor noise, EMI measures, mechanical resonance
Purpose of Use
Reduction of the motor noise
Measures against EMI and leakage
Reduce mechanical resonance
4.16.1 PWM carrier frequency and soft-PWM control (Pr. 72, Pr. 240)
You can change the motor sound.
PWM frequency selection
The above parameters can be set when Pr.160 User group read selection = "0". (Refer to page 179)
* The parameters in the table allow its setting to be changed during operation 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 EMI measures or on leakage current reduction caused by the PWM switching.
Soft-PWM control (Pr. 240)
Soft-PWM control is a control method that changes the motor noise from a metallic tone into an unoffending complex tone.
Decreasing the PWM carrier frequency effect on EMI measures and on leakage current reduction, but increases
When PWM carrier frequency is set to 1kHz or less (Pr.72 ≤ 1), fast response current limit may function prior to stall
prevention operation due to increase in ripple currents, resulting in insufficient torque. In such case, set fast-
response current limit operation invalid using Pr. 156 Stall prevention operation selection .
When setting 2kHz or more in Pr. 72 to perform operation in the place where the surrounding air temperature
exceeding 40°C, caution should be taken as the rated inverter current should be reduced. (Refer to page 302)
Parameters referred to
Pr. 156 Stall prevention operation selection
Motor noise, EMI measures, mechanical resonance
Parameter that should be Set
Carrier frequency and
Speed smoothing control
0 to 15
Refer to page 84
Pr. 72, Pr. 240
You can change the PWM carrier frequency.
The setting is in [kHz].
Note that 0 indicates 0.7kHz and 15
Soft-PWM is invalid
When Pr. 72 = "0 to 5", soft-PWM is valid.
Refer to Page