Motor Noise, Emi Measures, Mechanical Resonance; Pwm Carrier Frequency And Soft-Pwm Control (Pr. 72, Pr. 240) - Mitsubishi Electric FR-E700 Series Instruction Manual

Parameter
6.15

Motor noise, EMI measures, mechanical resonance

Purpose
Reduction of the motor noise
Measures against EMI and leakage cur-
rents
Reduce mechanical resonance
6.15.1

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

You can change the motor sound.
Pr. No. Name
PWM frequency
72
selection
Soft-PWM operation
240
selection
The above parameters can be set when Pr. 160 "User group read selection" = 0.
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".
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.
Soft-PWM control (Pr. 240)
Soft-PWM control is a control system that changes the motor noise from a metallic tone into an un-
offending complex tone.
NOTES
Decreasing the PWM carrier frequency reduces inverter-generated noise and leakage current, but
increases motor noise.
When PWM carrier frequency is set to 1kHz or less (Pr. 72 ≤ 1), fast response current limit may func-
tion 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 preven-
tion operation selection".
When setting 2kHz or more in Pr. 72 to perform operation in the place where the ambient temper-
ature exceeding 40°C, caution should be taken as the rated inverter current should be reduced.
(Refer to appendix A-1.)
FR-E700SC EC
Initial Value Setting Range
0–15
1
(integral value)
0
1
1
Motor noise, EMI measures, mechanical resonance
Parameters that must be set
Carrier frequency and Soft-PWM selection
Speed smoothing control
Description
PWM carrier frequency can be changed. The
setting displayed is in [kHz]. The settings indi-
cate the following frequencies:
0.......................0.7kHz
Settings between 1–14 correspond directly to
the frequency values.
15...................14.5kHz
Soft-PWM is invalid
When Pr. 72 = 0 to 5, Soft-PWM is valid.
Refer to
Section
Pr. 72, Pr. 240 6.15.1
Pr. 653 6.15.2
Parameters referred to
156 Stall prevention
operation selection
Refer to
Section
6.3.5
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