Design and control of a low power DC-AC converter fed by a photovoltaic array

In this paper, we present a DC-AC converter fed by a PV array for stand alone applications up to 50 W. It is dedicated to rural areas in countries having abundant sunshine and where there is no grid connection to the utility network or the power supply is weak as in many underdeveloped countries. Using a single PV array of 50 W as typical power, the aim is to have a simple system, robust, free-maintenance and highly efficient for cellar phone adapter e.g.. The design of the structure has led to a double boost for the DC-DC module (400 V as output voltage) where a high gain is needed. The DC-AC converter is made of a half-bridge inverter and an (LC) filter tuned for 50 Hz. Using simulation packages, we have obtained the power components parameters (inductances, switches and diodes) and set the switching frequency. For control purposes, a linear controller (PID type) is used and a non-linear approach using sliding mode is evaluated. Simulation results in terms of robustness and efficiency are promising.