The interfacing stability of photovoltaic cells and current-fed MPPT converter

Based on the stability analysis methodology for cascade converters, the photovoltaic (PV) interface stability of current-fed (CF) maximum power point tracking (MPPT) converter adding input capacitor is studied, and the interface voltage control loop design guideline is given in this paper. The interface stability criterion of cascade system composed of PV cells and the MPPT converter is deduced at first, and then the output impedance of photovoltaic cells and the closed-loop input impedance of the Boost converter adding input capacitor are analyzed. According to the stability criterion proposed here, the stability conditions together with the design guidelines-the controller parameter of the CF MPPT converter adding input capacitor should be design under the minimum interface voltage to ensure the converter maintain the PV interface stability in the entire input voltage range-for the MPPT converter are derived. The validity of the theoretical analysis has been verified by the experiments on a 150W prototype.