New multifunctional push-pull converter operating with MPPT and integrated energy storage system for PV micro-inverter applications

This paper presents a novel multifunctional push-pull converter for micro-inverter applications, used to interface photovoltaic (PV) modules and an battery energy storage system with the power grid (PG). The push-pull DC-DC power converter requires only two switching devices. It uses a specific algorithm to control the batteries charging process, preserving their lifetime, and also to operate as maximum power point tracker, optimizing the energy production from the PVs modules. The push-pull DC-AC power converter operates in coordination with the DC-DC converter, injecting all available energy from the PVs modules into the PG. If the produced energy exceeds the consumed energy, the surplus is used to charge the batteries for latter consumption. The proposed topology aims to contribute to the technological development in terms of power converters for micro-inverter applications. Throughout the paper is given a detailed explanation on the principle of operation of the new topology, as well as on the proposed digital control algorithm.