Delta Electronics AC Motor Drive VFD-E - Manual (Page 107)

Chapter 4 Parameters|
4-54 Revision June 2008, 04EE, SW--PW V1.11/CTL V2.11
1kHz
8kHz
15kHz
Carrier
Frequency
Acoustic
Noise
Electromagnetic
Noise or leakage
current
Heat
Dissipation
Current
Wave
Significant
Minimal Significant
Minimal
Minimal
Significant
Minimal
Significant
From the table, we see that the PWM carrier frequency has a significant influence on the
electromagnetic noise, AC motor drive heat dissipation, and motor acoustic noise.
The PWM carrier frequency will be decreased automatically by heat sink temperature and
output current of the AC motor drive. 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 50 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 chart. 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