Dynamic Characteristics of Current-Fed Superbuck Converter

A photovoltaic generator is internally a current source having features resembling either a current or voltage source depending on the operating point in respect to its maximum power point (MPP). Therefore, the MPP-tracking converter can be implemented either as a voltage-fed (VF) or current-fed (CF) converter. This paper investigates the dynamic properties of a CF superbuck converter developed from the corresponding VF superbuck converter by applying duality-transformation methods. The dynamic characterization of CF converters is not publicly presented earlier although the duality-transformation methods are known from late 1960s or even earlier. The investigations show that the state-space-averaging technique yields accurate dynamic models also in CF domain. Experimental evidence is provided based on a 400-kHz superbuck converter supplied by a real photovoltaic or solar generator and loaded by a storage battery.