Motor Noise, Emi Measures, Mechanical Resonance; Pwm Carrier Frequency And Soft-Pwm Control (Pr. 72, Pr. 240) - Mitsubishi Electric FR-E720-0.1 K Instruction Manual

4.16 Motor noise, EMI measures, mechanical resonance

Purpose of Use
Reduction of the motor noise
Measures against EMI and leakage
currents
Reduce mechanical resonance

4.16.1 PWM carrier frequency and soft-PWM control (Pr. 72, Pr. 240)

You can change the motor sound.
Parameter
Name
Number
72 * PWM frequency selection
Soft-PWM operation
240 *
selection
The above parameters can be set when Pr.160 User group read selection = "0". (Refer to page 183)
* 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.
(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.
(2) 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.
NOTE
Decreasing the PWM carrier frequency effect on EMI measures and on leakage current reduction, but increases
motor noise.
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 304)
Parameters referred to
Pr. 156 Stall prevention operation selection

Motor noise, EMI measures, mechanical resonance

Parameter that should be Set
Carrier frequency and
Soft-PWM selection
Speed smoothing control
Initial Value Setting Range
1 0 to 15
1
Refer to page 88
Pr. 72, Pr. 240
Pr. 653
Description
You can change the PWM carrier frequency.
The setting is in [kHz].
Note that 0 indicates 0.7kHz and 15
indicates 14.5kHz.
0 Soft-PWM is invalid
1 When Pr. 72 = "0 to 5", soft-PWM is valid.
Refer to Page
169
170
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169