3
vacon • 12
SPECIAL CHARACTERISTICS AFFECTING THE
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Figure 10. Simulated CM-voltage, U
dc
=1025V, fsw=5kHz.
Because of the common mode DC-link starts to jump compared to ground. Main frequency for this
jumping is switching frequency but also higher frequencies will be present. As an example, a typical
measured DC+ to ground voltage can be seen in Figure 11. A rule of thumb is that with a typical DC-
link voltage 1025V, the voltage spikes will be about 1.5kV.
#
Curve info
max
min
rms
......
U
DC
/2
171
171
171
----
U
DC
/6
512
512
512
___
CM voltage
512
-512
264
600
400
40
40.10 40.20 40.30
40.40 40.50
Time [ms]
40.60
40.70 40.80
40.90
41
200
0
-200
-400
-600
UDC/6
UDC/2
CM voltage
CM voltage
U [V]
Common mode
Содержание NX6
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