ABSTRACT
This paper introduces and describes two new Maximum Power Point Tracking (MPPT) methods: The Cross-Correlation Method and The Conductance Variation Method. The proposed methods take properly advantage of the direction of the conductance growth and the behavior presented by the photovoltaic (PV) system when operating at the constant current or voltage portion of the IxV characteristic curve. The proper evaluation of the effects of a small perturbation signal applied to the PV system is the basis of the proposed methods. The nature of the perturbation signal distinguishes the introduced methods from the conventional ones in the sense that only the resulting variation of the PV system voltage and current is required as the input variables of the control loops. The methods do not require either a fix step perturbation signal or look-up tables. These information are extracted from the PV system itself and are properly manipulated by the introduced control loop, which demands only an integral controller or a first order low-pass filter. No additional dedicated converter is required and the interaction with inverter control is straightforward.
