Pwm Carrier Frequency And Soft-Pwm Control - Mitsubishi Electric 800 Series Instruction Manual

5.7.15

PWM carrier frequency and Soft-PWM control

The motor sound can be changed.
Pr. Name
72
PWM frequency selection
E600
240 Soft-PWM operation
E601 selection
260 PWM frequency automatic
E602 switchover

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
Pr.72 setting Real sensorless vector control,
0 to 5 2
6 to 9 6

10 to 13 10

14, 15 14


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.)
Initial value Setting range
0 to 15
2
0 to 6, 25
0
1
1
0
1
1
PM sensorless vector control
vector control
2
6
10
14
(E) Environment setting parameters
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.)
Soft-PWM disabled
The soft-PWM is enabled.
PWM carrier frequency automatic reduction function
disabled (for the LD, ND, or HD rating)
PWM carrier frequency automatic reduction function
enabled
Carrier frequency (kHz)
Description
page 137.)
Fast-response mode
4
261
PARAMETERS
5
GROUP
E