An Efficient Grid-tied Flyback Micro-inverter with DCM Control Strategy

Abstract

In two-stage micro-inverter photovoltaic (PV) applications, DC/DC converter is used to obtain the highest DC power from the PV module. In this type of inverter, the rising of voltage from the PV module to a grid voltage level is limited to a certain value. Moreover, the absence of the isolation between the input and output makes it is less efficient. For these reasons, an efficient single-stage grid-tied flyback PV micro-inverter with discontinuous conduction mode (DCM) control strategy is proposed to feed an alternating current (AC) to the main grid with a lower value of the total harmonic distortion (THD). The control strategy is based on a sine sinusoidal pulse width modulation (SPWM) technique to control the main switch of flyback inverter. Also, a simple perturb and observe (P&O) maximum power point tracking (MPPT) technique has been presented to obtain the MPP point from the PV module for any environmental conditions. The proposed control was verified using PSIM software and simulation results is obtained. The proposed control is tested under different weather conditions for solar irradiance and temperature, as a result, a pure sin wave current has been injected into the grid with a lower harmonics value. Finally, the small size, low cost and high reliability of single stage flyback micro-inverter is presented without the need for DC/DC converter.