Input Control of Photovoltaic Fed DC-DC Converter Based on a Dual Modeling Approach

Abstract

The non-linear characteristic of photovoltaic (PV) sources with a clear dual nature on both side of their maximum power point complicates the interfacing converter design, especially in the case of maximum power point tracking MPPT. To overcome such constraint, in the current study, two distinct input controllers of the PV fed converter are used. The first one designed assuming a current fed topology, and the second assuming a voltage fed one. The probable oscillation in the neighborhood of the maximum power point is reduced by imposing a hysteresis band, to allow a soft transient from one region to the other one. The converter is modeled following a state-space averaging method, where the resulting transfer functions describe fully the converter internal dynamics. The control issue of the resulting dual model is discussed, and a frequency approach is used, where the system loop gain transfer function is shaped for the best possible performances. The validity of the modeling and the controllers design approach are finally tested by both model simulation and experimental tests under open and closed loop conditions.
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