The effect of control loops form of the interface converter in output voltage regulation mode on the operating characteristics of photovoltaic cells

The operating characteristics of photovoltaic (PV) cells are essential to the design of steady-state characteristics and control parameters of the interface converter in output voltage regulation (OVR) mode. From the perspective of output voltage closed-loop control stability, the effect of control loops form of the interface converter in OVR mode on the operating characteristics of PV cells is studied in depth in this paper. The external characteristic of PV interface converter and three kinds of control system arrangements to satisfy such characteristic are analyzed in detail at first. Then, the Boost converter adding an additional input capacitor is taken as an example, and its small signal model including the dynamic equivalent circuit of PV cells is built up. After that, the closed-loop transfer functions of the converter operating in continuous conduction mode (CCM) with different control loops form are deduced. Finally, according to the Routh criterion, the essential condition for output voltage control stability is analyzed and the relations between control loops form of the interface converter in OVR mode and the operating characteristic of PV cells are deduced. The validity of the theoretical analysis has been verified by the experiment results of a 100W prototype.