Impedance specification and impedance improvement for DC distributed power system

In a DC distributed power system, the interaction between individually designed power modules/subsystems may cause the instability of the whole system. In the small-signal sense, these kinds of interactions can be predicted by checking impedance ratio Z/sub o//Z/sub i/ and can also be prevented by making impedance specification for power modules/subsystems. Many efforts have been made in defining impedance specification and improving I/O impedance for converters and filters. This paper summarizes work in these two areas.