A new scheme for maximum photovoltaic power tracking control

It is shown that the derivative (dp/sub s//de/sub s/) of output power (p/sub s/) with respect to output voltage (e/sub s/) of a photovoltaic array is equal to zero at the maximum power point. This kind of relationship is independent of insolation and temperature. This property may be utilized to perform maximum power tracking control, that is, at all insolation and temperature levels, the maximum power point can be obtained by regulating dp/sub s//de/sub s/ toward zero. Based on this concept, a new scheme of maximum power tracking control is proposed and applied to a utility-interactive photovoltaic power conditioning system, where the boost chopper is responsible for maximum power tracking control and the inverter responsible for unity power factor control and constant DC input voltage control. The related design method is described. The usefulness and validity of the proposed method are verified by simulation. Compared to conventional methods, this method show a considerably high tracking performance.