dU/dt filter range
vacon •
5
Local contacts: http://drives.danfoss.com/danfoss-drives/local-contacts/
2
Figure 1. Change of the voltage shape in winding
Voltage
stress
Figure
2.
Voltage
pulse
reflection
The maximum value of the reflected voltage is 2 x DC link voltage, in practice 1.8-1.9 x
Udc. The voltage is fully developed at cables that are > 5 m.
Note that the DC link voltage is increased if the supply is higher or if an active front
end maintains a high DC link voltage. If this voltage stress is too high, it is
recommended to use the dU/dt filter.
A dU/dt filter is an undamped serial LC type filter, with a resonance frequency
between 120kHz and 160kHz. This will limit the voltage rise speed to < 1000 V/us.
