Hitachi WJ200-001S Instruction Manual page 154

Carrier frequency (PWM) related
Carrier frequency adjustment:  – The internal
circuitry (also called the
the lower AC power frequency of the inverter "rides" the carrier. The faint, high-pitched
sound you hear when the inverter is in Run Mode is characteristic of switching power
supplies in general. The carrier frequency is adjustable from 2.0kHz to 15kHz. The
audible sound decreases at the higher frequencies, but RFI noise and leakage current
may be increased. Refer to the specification derating curves in Chapter 1 to determine
the maximum allowable carrier frequency setting for your particular inverter and
environmental conditions. Refer also to  for automatic carrier frequency reduction.
NOTE: The carrier frequency setting must stay within specified limits for
inverter-motor applications that must comply with particular regulatory agencies. For
example, European CE-approved application requires the carrier to be 3kHz or less.
Automatic carrier frequency reduction:  – The automatic carrier frequency
reduction automatically reduces the carrier frequency according to the increase in
output current. To enable this function, specify "" for automatic carrier frequency
reduction selection ().
When the output current increases to 60%,
72%, 84%, or 96% of the rated current, this
function reduces the carrier frequency to 12,
9, 6, or 3 kHz, respectively. This function
restores the original carrier frequency when
the output decreases to 5% lower than each
reduction start level.
The rate of carrier frequency reduction is
2kHz per second. The maximum limit of
carrier frequency change by this function is
the value specified for the carrier frequency setting (); the minimum limit is 3 kHz.
Note: If 3 kHz or less freq. has been specified for , this function is disabled
regardless of the setting of .
[Remark: Above graph is for schematic concept and the profile is a subject to change
reflecting the temperature test. ]
Func.
Name
Code
Carrier frequency

Automatic carrier

frequency reduction
chopper frequency
"b" Function
Description
Sets the PWM carrier (internal
switching frequency), range is 2.0
to 15.0 kHz
Three option codes:
Disabled
Enabled, depending on the
output current
Enabled, depending on the
heat-sink temperature
switching frequency
). It is called the carrier frequency because
Carrier freq.
5%
15kHz
12kHz
9kHz
6kHz
3kHz
0
50
60%
Run
Mode
Edit


369
of the inverter
5%
5%
5%
100
72% 84% 96%
Output current
Defaults
Initial data Units
10.0 kHz
01 