Harmonic filtering in power applications

One suggested solution to line-current harmonics injected by rectifying power converters is the placement of series-resonant filters across the line supply feeders. For effective filtering, the filter impedance level must be comparable to the source impedance. A useful design parameter for the filter impedance level is the characteristic resistance or impedance. An example of personal computer power supplies is used to indicate the degree of harmonic filtering achieved as a function of this characteristic resistance. Computer analysis using PSPICE shows that the reduction in harmonics produced by filters is achieved at the expense of large increases in the active component of line current. This increase can require much larger supply conductors