A DC link choke is an electrical device that filters and controls the DC bus voltage and current in a variable frequency drive. The function similarly to AC line reactors, in that they smooth the current flow to the VFD and reduce harmonic distortion on the power line.
Installed between the input rectifier and bus capacitor, DC link chokes simultaneously improve the DC bus waveform and the AC input waveform. Because they require just one coil, versus three in an AC reactor, they are generally a less expensive option for filtering current to a drive. Their location in the circuit also prevents voltage drop to the drive, eliminating nuisance faults.
DC link chokes are differentiated by percent impedance, determining the maximum value of current that will flow under fault conditions. Current rating typically extends up to 1000A depending on the size of the component.