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

Motor noise, EMI measures, mechanical resonance

6.15 Motor noise, EMI measures, mechanical resonance
Purpose
Reduction of the motor noise
Measures against EMI and leakage
currents
Reduce mechanical resonance
6.15.1

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

You can change the motor sound.
Pr.
Name
No.
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 unoffending complex tone.
NOTES
Decreasing the PWM carrier frequency reduces inverter-generated noise and leakage cur-
rent, 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 ambient
temperature exceeding 40°C, caution should be taken as the rated inverter current should
be reduced. (Refer to appendix A-1.)
6 - 172
Parameters that must be set
Carrier frequency and Soft-PWM selection
Speed smoothing control
Initial
Setting Range
Value
0–15
1
(integral value)
0
1
1
Description
PWM carrier frequency can be
changed. The setting displayed is in
[kHz]. The settings indicate the fol-
lowing 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.
Parameter
Refer to
Section
Pr. 72, Pr. 240 6.15.1
Pr. 653 6.15.2
Parameters referred to
156 Stall prevention
operation selec-
tion
Refer to
Section
6.3.5