Single stage inverter for PV applications with One Cycle Sampling technique in the MPPT algorithm

This paper introduces a single-stage, single-phase, inverter, for maximum efficient photovoltaic grid connection. The inverter is based in a full-bridge converter where a few diodes and one inductor have been added to enable single stage operation. The new topology provides an additional buck-boost converter function at the bridge level in order to extract the maximum power from photovoltaic (PV) panel. Non linear control is used to regulate the sinusoidal current injected in the grid and the PV voltage, so that maximum power point tracker, MPPT, is obtained. The new MPPT algorithm uses one cycle sampling technique to obtain the average value of the voltage and current in the panel with a small time delay. This technique eliminates errors introduced in the MPPT calculation, due to the switching ripple. The proposed algorithm also allows the operation of the control circuit at a lower frequency than the high switching frequency of the bridge converter transistors.