Operation And Modelling Of The Unloaded Bi-Directional DC/DC Converter Performing As An Active Damping Function In A Simple DC System

The sub-system interaction and instability phenomena is a common problem in the distributed power system (DPS). The instability phenomena that occur in the DC bus bar of a DPS are mainly due to a negative incremental input impedance characteristic of a connected constant power load (CPL). The CPL has such a characteristic due to its internal control function such as to regulate the converter output voltage, which results in the converter tends to draw a constant power. This paper briefly presents the instability phenomena due the CPLs and the modelling of a DC-DC converter to behave as an damping network, purposely to eliminate the instability in a simple system comprising L-C filters and a CPL. The modelling of the DC-DC converter using the state averaging and linearizing technique is discussed. A small-signal converter model was derived and the factors that may affect its performance were obtained. The obtained model of the DC-DC converter can be used to design of the controller.