Mitsubishi Electric 800 Series, Instruction Manual, Page: 262 / 727

(E) Environment setting parameters
PARAMETERS
261
5
GROUP
E
5.7.15
PWM carrier frequency and Soft-PWM control

The setting range for the FR-A860-01080 or lower.

The setting range for the FR-A860-01440 or higher.
 Changing the PWM carrier frequency (Pr.72)
• The PWM carrier frequency of the inverter can be changed.
• Changing the PWM carrier frequency can be effective for avoiding the resonance frequency of the mechanical system or
motor, as a countermeasure against EMI generated from the inverter, or for reducing leakage current caused by PWM
switching.
• Under Real sensorless vector control, vector control, and PM sensorless vector control, the following carrier frequencies
are used. (For the control method and fast-response mode selection, refer to Pr.800 Control method selection page 137 .)

In the low-speed range (3 Hz or lower) under Real sensorless vector control, the carrier frequency is automatically changed to 2 kHz. (For FR-
A860-00170 or lower)
NOTE
• In the low-speed range (about 10 Hz or lower), the carrier frequency may be automatically lowered. Motor noise increases,
but not to the point of failure.
 Soft-PWM control (Pr.240)
• Soft-PWM control is a control method that changes the motor noise from a metallic sound into an inoffensive, complex tone.
• Setting
Pr.240 = "1" will enable the Soft-PWM control.
• To enable the Soft-PWM control for the FR-A860-01080 or lower, set Pr.72 to "5 kHz or less".
To enable it for the FR-A860-01440 or higher, set Pr.72 to "4 kHz or less".
 PWM carrier frequency automatic reduction function (Pr.260)
• Setting Pr.260 ="1 (initial value)" will enable the PWM carrier frequency auto-reduction function. If a heavy load is
continuously applied while the inverter carrier frequency is set to 3 kHz or higher ( Pr.72

"3"), the carrier frequency is
automatically reduced to prevent occurrence of the inverter overload trip (electronic thermal O/L relay function) (E.THT).
The carrier frequency is reduced to as low as 2 kHz. (Motor noise increases, but not to the point of failure.)
The motor sound can be changed.
Pr. Name Initial value Setting range Description
72
E600
PWM frequency selection
2
0 to 15

The PWM carrier frequency can be changed. The
setting displayed is in [kHz]. Note that 0 indicates 0.7
kHz, 15 indicates 14.5 kHz, and 25 indicates 2.5
kHz. (The setting value "25" is for manufacturer
setting. Do not set.)
0 to 6, 25

240
E601 Soft-PWM operation
selection
1
0 Soft-PWM disabled
1 The soft-PWM is enabled.
260
E602 PWM frequency automatic
switchover
1
0
PWM carrier frequency automatic reduction function
disabled (for the LD, ND, or HD rating)
1
PWM carrier frequency automatic reduction function
enabled
Pr.72 setting
Carrier frequency (kHz)
Real sensorless vector control,
vector control
PM sensorless vector control Fast-response mode
0 to 5 2 2
4
6 to 9 6

6
10 to 13 10

10
14, 15 14

14