A double stage micro-inverter for optimal power flow control in grid connected PV system

This paper presents a double-stage micro-inverter with an isolated Sepic converter used for optimal power flow control in a small grid connected PV system. The proposed micro-inverter has two stages. Stage I is a DC-DC converter with isolated Sepic transformer and stage II is a DC-AC converter based on voltage source inverter. The main features of the proposed inverter include: high efficiency, small dimension, low cost, lightweight, and a stable AC current injection. Three controllers used comprise non-MPPT (Maximum Power Point Tracker), Constant Voltage (CV), Perturb & Observe (P&O), and Incremental Conductance (IC). To validate the effectiveness of the design, such methods are examined under different irradiance. The results show that the designed micro-inverter controlled by IC MPPT method has satisfactory performance and the efficiency is relatively higher than that of non-MPPT, CV or P&O method. Thus, it can be used as an alternative solution of micro-inverter topology.