Chapter 4 Parameters
4-73
02.18
Selection for Carrier Modulation
Factory Setting: 0
Settings
0
By carrier modulation of load current and temperature
1
By carrier modulation of load current
Setting 0: The PWM carrier frequency (Fc) will be decreased automatically by heat sink
temperature and output current of the AC motor drive. Please refer to the following figure for
the decreasing the PWM carrier frequency. It is used as a necessary precaution to prevent the
AC motor drive from overheating and thus extends IGBT’s life. Example for 460V models:
Assume the carrier frequency to be 15kHz, the ambient temperature is 35 degrees C with a
single AC motor drive(mounting method A). If the output current exceeds 80% * rated current,
the AC motor drive will decrease the carrier frequency automatically according to the following
figure. If output current is 100% * rated current, the carrier frequency will decrease from 15kHz
to 12kHz.
Mounting method
Method A
120mm
120mm
50
m
m
50
m
m
150mm
150mm
50
m
m
50
m
m
Frame B & C
Frame A
Frame A
Method B
Frame B & C
The relation between rated current and carrier frequency
