Mitsubishi Electric FR-A800 Series Instruction Manual page 358

 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 on
Pr.72 setting
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
*1 When low-speed range high-torque characteristic is disabled (Pr.788 = "0"), 2 kHz is used.
*2 In the low-speed range (less than 3 Hz) under Real sensorless vector control, the carrier frequency is automatically changed to 2 kHz.
(For the FR-A820-00490(7.5K) or lower and the FR-A840-00250(7.5K) or lower)
• When using an optional sine wave filter (MT-BSL/BSC), set "25" (2.5 kHz) in Pr.72. (FR-A820-03800(75K) or higher, FR-
A840-02160(75K) or higher.)
NOTE
• In the low-speed range (less than about 10 Hz), the carrier frequency may be automatically lowered.
Motor noise increases, but not to the point of failure.
• When Pr.72 = "25", the following limitations apply.
-
-
-
 Soft-PWM control (Pr.240)
• Soft-PWM control is a function 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, set Pr.72 to 5 kHz or less for the FR-A820-03160(55K) or lower or the FR-A840-
01800(55K) or lower. For the FR-A820-03800(75K) or higher or the 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.
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Real sensorless vector control,
Vector control
2
*2
6
*2
10
*2
14
V/F control is forcibly set.
Soft-PWM control is disabled.
The maximum output frequency is 60 Hz.
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Carrier frequency (kHz)
PM sensorless vector control,
*1
6
6
10
14
page 221.)
Fast-response mode
4
8
12
5. PARAMETERS
5.7 (E) Environment setting parameters
1
2
3
4
5
6
7
8
9
10
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