Motor Noise, Noise Reduction; Pwm Carrier Frequency And Soft-Pwm Control (Pr. 72, Pr. 240) - Mitsubishi Electric FR-A720-0.4K Instruction Manual

4.20 Motor noise, noise reduction

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

You can change the motor sound.
Parameter
Name
Number
72 PWM frequency selection
*1
240 Soft-PWM operation selection
*1
*1 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.
(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 reducing noise or leakage current generated from the inverter.
⋅ Carrier frequencies under real sensorless vector control or vector control are as shown below.
Pr. 72 Setting
55K or less
0 to 5
6 to 9
10 to 13
14, 15
⋅ When using an option sine wave filter (MT-BSL/BSC) for the 75K or more, set "25" in Pr. 72 (2.5kHz).
REMARKS
When "25" (available with the 75K or more) is set in Pr. 72, V/F control is forcibly selected.
(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.
CAUTION
⋅ For the 75K or more inverter, reduce the rated inverter output current to use when the carrier frequency is set to 3kHz or more
(Pr. 72 ≥ "3"). (Refer to page 420)
⋅ 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 (
operation due to increase in harmonic currents depending on the motor, resulting in insufficient torque. In such case, set fast
response current limit operation invalid using
♦ Parameters referred to ♦
Pr. 156 Stall prevention operation selection
Initial
Setting Range
Value
55K or less
2
75K or more
0
1
1
Carrier Frequencies (kHz)
75K or more
0 to 5
6
⎯
⎯
≤ 1), fast response current limit may function prior to stall prevention
Pr. 72
Pr. 156
Stall prevention operation selection
Refer to page 148

Motor noise, noise reduction

Description
0 to 15 PWM carrier frequency can be changed.
The setting displayed is in [kHz]. Note
that 0 indicates 0.7kHz, 15 indicates
0 to 6, 25
14.5kHz and 25 indicates 2.5kHz.
Soft-PWM is invalid
When Pr. 72 = "0 to 5" (
more), soft-PWM is valid.
2
6
10
14
.
" "
0 to 4 for 75K or
4
273