Step-down maximum power point tracker for photovoltaic systems

Abstract A design of a simple, inexpensive, and efficient maximum power point tracker (MPPT) is presented. This design calls for a fixed voltage and a pilot cell to track the maximum power point voltage (Vmp). The tracking is done by changing the duty cycle of a step-down chopper, which is controlled by a direct feedback analog circuit. The control voltage of the tracker is the open circuit voltage (Voc) of the pilot cell multiplied by a constant. This constant is preadjusted so that it tracks the Vmp of the array in response to any changes due to temperature or insolation. This MPPT can also function as a voltage regulator for battery charging.