Motor Noise, Noise Reduction; Pwm Carrier Frequency And Soft-Pwm Control (Pr.72, Pr.240, Pr.260) - Mitsubishi Electric F700 Instruction Manual

Motor noise, noise reduction

3.14 Motor noise, noise reduction

3.14.1 PWM carrier frequency and Soft-PWM control (Pr.72, Pr.240, Pr.260)

You can change the motor sound.
Pr.71
page 80
Pr.73 Parameter
page 127
Number
Pr.239
page 67
Pr.241
72 * PWM frequency selection
page 129
Pr.259
page 211
Pr.261
page 112
240 * Soft-PWM operation selection
PWM frequency automatic
260
switchover
The above parameters can be set when Pr. 160 User group read selection = "0". (Refer to page 140.)
* 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.
⋅ When using an option sine wave filter (MT-BSL/BSC) for the 01800 or more, set "25" in Pr.72 (2.5kHz).
(2) 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.
(3) PWM carrier frequency automatic reduction function (Pr.260)
⋅ When continuous operation is performed at 85% or more of the inverter rated current (the parenthesized value
of the rated output current on page 248 or more) with the carrier frequency of the inverter set to 3kHz or more (Pr.
72 ≥ "3"), the carrier frequency is automatically reduced to 2kHz to protect the output transistor of the inverter.
(Motor noise increases, but it is not a failure)
⋅ When Pr. 260 is set to"0", the carrier frequency becomes constant (Pr. 72 setting) independently of the load,
making the motor sound uniform.
Note that continuous operation should be performed at less than 85% of the inverter rating.
CAUTION
⋅ Decreasing the PWM carrier frequency reduces inverter-generated noise and leakage current, but increases motor noise.
⋅ When Pr. 570 = "0" (initial value), functions of Pr. 260 become invalid. PWM carrier frequency automatically decreases when
load increases. (Refer to page 61.)
124
Name Initial Value
2
1
1
Setting Range
01160 or PWM carrier frequency can be
0 to 15
less changed. The setting displayed is in
[kHz]. Note that 0 indicates 0.7kHz,
01800 or
15 indicates 14.5kHz and 25
0 to 6, 25
more
indicates 2.5kHz.
0 Soft-PWM is invalid
When Pr. 72 = "0 to 5", soft-PWM is
1
valid.
PWM carrier frequency is constant
0
independently of load.
Decreases PWM carrier frequency
1
automatically when load increases.
Description