Pwm Carrier Frequency And Soft-Pwm Control; Changing The Pwm Carrier Frequency; Soft-Pwm Control - Mitsubishi FR-A800 Instruction Manual

5.7.17

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-A820-03160(55K) or lower and FR-A840-01800(55K) or lower.

The setting range for the FR-A820-03800(75K) or higher and FR-A840-02160(75K) and 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


When low-speed range high-torque characteristic is disabled (Pr.788="0"), 2 kHz is used.

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-A820-00490(7.5K) or lower and FR-A840-00250(7.5K) or lower)
• When using the optional sine wave filter (MT-BSL/BSC), set Pr.72 = "25" (2.5 kHz). (FR-A820-03800(75K) or higher, FR-
A840-02160(75K) or higher.)
NOTE
• When Pr.72="25", the following limitations apply.
- V/F control is forcibly set.
- Soft-PWM control is disabled.
- The maximum output frequency is 60 Hz.
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-A820-03160(55K) or lower and FR-A840-01800(55K) or lower, set Pr.72 to "5
kHz or less".
To enable it for the FR-A820-03800(75K) or higher and FR-A840-02160(75K) or higher , set Pr.72 to "4 kHz or less".
NOTE
• While a sine wave filter (Pr.72 = "25") is being used, the Soft-PWM control is disabled.
Initial value Setting range
0 to 15
2
0 to 6, 25
0
1
1
0
1
1
PM sensorless vector control
vector control
6

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 the sine wave

filter.)
Soft-PWM disabled
The soft-PWM is enabled.
The PWM carrier frequency is constant regardless of
the load.
When the carrier frequency is set to 3 kHz or higher
(Pr.72 3), perform continuous operation at less
than 85% of the inverter rated current.
When the load increases, the PWM carrier
frequency is reduced.
Carrier frequency (kHz)
Description
page 164.)
Fast-response mode
4
277
PARAMETERS
5
GROUP
E