430
PARAMETER
2.20.8 PWM carrier frequency and Soft-PWM control [Pr. 72, 240, 260
*
]
(common)
You can change the motor sound. Increasing PWM carrier frequency will reduce the motor acoustic noises, but increases EMI
and leakage current from the inverter.
(1) PWM carrier frequency changing [
Pr. 72
]
You can change the PWM carrier frequency of the
inverter.
Changing PWM carrier frequency is useful for the
following purposes:
•To avoid mechanical or motor resonance
•To prevent EMI
•To reduce leakage current by PWM switching
When using an option sine wave filter (MT-BSL/BSC)
for the 75K or more, set [
Pr. 72 = 25 (2.5kHz)
]. When
[
Pr. 72 = 25
], V/F control is forcibly selected. At this
time, perform continuous operation at less than 90%
of the rated inverter output current.
When the carrier frequency is set to 3kHz or more
([
Pr. 72 3
]) to the 75K or more
inverter,
perform continuous operation at less than 85% of the
rated inverter output current.
Carrier frequencies under Real sensorless vector
control and vector control by
are as shown
below.
When PWM carrier frequency is set to 1kHz or less
([
Pr. 72 1
]), fast-response current limit may function
before stall prevention operation due to increased
ripple current, and torque may be insufficient. In such
case, set fast-response current limit operation invalid
using [
Pr. 156 Stall prevention operation selection
] .
(2) Soft-PWM control [
Pr. 240
]
Soft-PWM control is a control method that changes
the motor noise from a metallic tone into an
unoffending complex tone.
(a) With Soft-PWM
Since the frequency components are
dispersed, the sound becomes inoffensive
with less metallic noises.
(b) Without Soft-PWM
Since the frequency components are
concentrated, metallic noises are generated.
Motor noises data example
(When the motor SF-JR 4P 3.7kW carrier frequency
2kHz is used)
(* [Pr. 260] is not available for
.)
common
A700
E700
[Pr. ]
Name
Initial
Value
Setting Range
Description
Available Inverters
72
*
PWM frequency
selection
2
55K or
less
0 to 15
PWM carrier frequency can be changed. The
setting displayed is in [kHz].
Note that 0 indicates 0.7kHz, 15 indicates 14.5kHz
and 25 indicates 2.5kHz.
(25 is exclusively for a sine wave filter.)
{
{
{
{
75K or
more
0 to 6,
25
240
*
Soft-PWM
operation
selection
1
0
Soft-PWM is invalid
{
{
{
{
1
When [
Pr. 72 = 0 to 5
] (0 to 4 for the 75K or more),
Soft-PWM is valid.
260
PWM frequency
automatic
switchover
1
0
0
PWM carrier frequency is constant independently
of load.
Operate continuously at less than 85% of the
inverter rated current when carrier frequency is set
3kHz or more ( [
Pr. 72
3
] ) in
.
—
{
—
{
1
Decreases PWM carrier frequency automatically
when load increases.
* The parameters in the table allow its setting to be changed during operation even if [
Pr. 77 Parameter write selection = 0
] (initial value).
A700
F700
E700
D700
F700
D700
F700
[Pr. 72] Setting
Carrier Frequency (kHz)
55K or
less
75K or
more
0 to 5
0 to 5
2
6 to 9
6
6
10 to 13
—
10
14, 15
—
14
A700
A700
0
2k
4k
6k
8k
10k
12k 0
2
4
0
6k
2k
4k
12k
8k
10k
Frequency [Hz]
Time [ s]
Noise level
0
2k
4k
6k
8k
10k
12k 0
2
4
0
6k
2k
4k
12k
8k
10k
Frequency [Hz]
[ s ]
Noise
Time
level
Summary of Contents for FR-A700 Series
Page 245: ...279 2 PARAMETER PARAMETER MEMO ...
Page 440: ...474 PARAMETER MEMO ...
Page 522: ...556 SELECTION MEMO ...
