8.24.3 Damping of Resonance due to Output Cable
Damping of Resonance due to Output Cable
With SINAMICS Perfect Harmony™ GH180 drives, the output lter can cosnsist of a reactor-
capacitor (LC) lter or a reactor only (L) lter. When a LC lter is used, the resonance due to the
lter can be damped by the drive using the parameters in the "Output Connection" Menu and
with "Filter CTs" selected for the "Filter Currents Source" parameter (ID 2918)
When an output reactor (L only) is used as the output lter, the output cables may or may not
introduce a resonance frequency that interacts with the control of th drive. Typically, an
interaction with the drive control occurs when the resonance frequency of the output circuit
(including the lter reactor and output cables) is around 1 kHz or lower. In such cases,
capacitance of the output cables is in the same range as the capacitance in a typical output
lter. The resonance frequency can be damped by the drive when "Output CTs" is selected in the
"Filter Currents Source" parameter (ID 2918). When this selection is made, the control uses
information in the output current to create a virtual resistor for damping the resonance.
Parameters that need to be entered are:
Cable Inductance - (ID 2941) This should represent the total inductance in the output circuit (including cable
inductance and any output transformer inductance). Enter in percent of drive
base inductance.
Filter Inductance - (ID 2920) Set the output lter inductor (i.e., impedance value as a ratio of the base output
impedance of the drive, typically 5 %)
Filter Capacitance - (ID 2930) Set the lter capacitance parameter to the output cable parasitic capacitance as
a ration of the base output admittance of the drive. Admittance is the inverse of
impedance.
Filter Damping Gain - (ID 2950) Contact Customer service for detailed information.
8.24.4 Operating Parallel Motors over Long Cables
The drive has the capability to operate parallel induction motors over long cables using the cable
inductance compensation parameter (2941).
For operation with two parallel motors connected to the same drive to work correctly the cable
length and characteristic requirements must be met.
Additional output ltering may be required for extremely long cables to compensate for
transmission line eects of the cable impedances and length. Siemens will calculate the
impedance values and need for ltering.
Stability can be an issue due to cable resonance. This is helped by reducing the current loop gains
and reducing the dead time compensation as needed.
Advanced Operating Functions
8.24 Long Cable Applications
NXGPro+ Control Manual
334 Operating Manual, A5E50491925A
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