6. Control Functions and Parameter Settings
6-37
B00-7
Carrier frequency
B01-7
The PWM carrier frequency and control method can be changed to change the tone of the
magnetic sound generated from the motor. The relation of the setting range and control
method is shown below.
1.0 to 15.0 : Mono sound method (Actual carrier frequency: 1.0 to 15.0kHz)
15.1 to 18.0 : Soft sound method 1 (Basic carrier frequency: 2.1 to 5.0kHz)
18.1 to 21.0 : Soft sound method 2 (Basic carrier frequency: 2.1 to 5.0kHz)
[Mono sound method]
This control method has a constant PWM carrier frequency. When a low carrier frequency is
set, an annoying magnetic sound may be generated.
[Soft sound method]
This control method changes the PWM carrier frequency at a fixed cycle, producing a softer
sound and lower electrical noise than the mono-sound method..
(Note 1)
There are cases when the setting value and actual carrier frequency (reference
carrier frequency for soft sound method) differ. Confirm the actual carrier
frequency with D03-3.
(Note 2)
In some cases the effect of noise onto the inverter's peripheral devices can be
reduced by lowering the carrier frequency.
(Note 3)
In applications using sudden acceleration/deceleration with the overcurrent limit
function in the V/f control mode (C30-0 = 1, 2), or in applications requiring a high-
speed response in the speed sensor-less vector control mode (C30-0 = 3),
setting a carrier frequency of 4.0kHz or more in the mono sound method is
recommended.
(Note 4)
If set to higher than the specified carrier frequency, the output current must be
derated. Refer to Fig. 1-2 in Appendix 1 for details.
(Note 5)
If the heat sink temperature 70°C is exceeded and the output current exceeds
90%, the carrier frequency will automatically change to 4kHz.