New multifunctional isolated microinverter with integrated energy storage system for PV applications

This paper proposes a novel multifunctional isolated microinverter which is able to extract the maximum available power from a solar photovoltaic module and inject it into the power grid, while simultaneously charging a battery energy storage system (BESS). The proposed microinverter integrates a novel DC–DC power converter and a conventional DC–AC power converter. The DC–DC power converter is able to send electrical energy to the secondary side of a high-frequency transformer and to the BESS, using only two power switches. Throughout this paper, the converter topology, the operation modes, the control algorithms, and the development of a laboratory prototype of the proposed microinverter are described in detail. Moreover, simulation and experimental results are presented to demonstrate the feasibility of the proposed solution.This work has been supported by FCT—Fundação para a Ciência e Tecnologia within the R&DUnits Project Scope: UIDB/00319/2020. This work has been supported by the FCT Project QUALITY4POWERPTDC/EEI-EEE/28813/2017. Luis A. M. Barros is supported by the doctoral scholarship PD/BD/143006/2018 granted by the Portuguese FCT foundation. Mohamed Tanta was supported by FCT PhD grant with a reference PD/BD/127815/2016 granted by the Portuguese FCT agency. Tiago J. C. Sousa is supported by the doctoralscholarship SFRH/BD/134353/2017 granted by the Portuguese FCT agency

Single Stage Flyback Micro-Inverter for Solar Energy Systems

ABSTRACT Solar energy systems based on photovoltaic (PV) cells have attracted considerable interest in recent years due to their promise of clear and seemingly limitless generated energy. Solar energy systems based on micro-inverter architectures are gaining in popularity as they are less prone to shading and PV cell malfunction since each solar panel in a system has its own low power inverter. A number of micro-inverters are single stage flyback inverters that are based on the DC-DC flyback topologies. There have been numerous papers on the topic of how to improve the efficiency of dc-dc flyback converters but as far as improving the efficiency of dc-ac flyback micro-inverter is concerned, comparatively less investigation on efficiency improvement has been performed. A low cost technique for improving the efficiency of a basic dc-ac flyback micro-inverter is proposed in the paper. The proposed efficiency improving technique is based on a simple snubber, consisting of just a few passive elements. In the thesis, the flyback micro-inverter with the passive snubber is presented; the modes of operation of the converter are discussed as well as the design of the converter with the passive snubber. Experimental results obtained from a lab prototype are presented as well. A second novel technique for improving the efficiency of a single stage flyback micro-inverter is also proposed. The technique is based on combining the simple passive snubber with a variable frequency control zero-voltage switching (ZVS) technique. In the thesis, the operation of the micro-inverter with both the passive snubber and the ZVS technique is explained and the design of the converter is discussed. Experimental results obtained from a lab prototype are presented to confirm the effectiveness of the both the techniques

Microinverter Topology Based Single-Stage Grid-Connected Photovoltaic System: A Review

This paper discussed the topology development of a single-stage microinverter in grid-connected PV system. In general, the microinverter topologies can be categorized into four type of topologies: 1) Flyback inverter, 2) Double-boost inverter, 3) Derived zeta-cuk configuration and 4) Buck-boost inverter. Flyback configuration is widely used for single-stage microinverter which offers protection between solar panel and utility grid. However due to the bulkiness of the transformer, new arrangement circuit employ the Half-Bridge topology with film capacitor and microcontroller provide a good room for research and future developments to obtain greater efficiency and compact design of single-stage microinverter grid-connected PV system. Plus, there are several characteristics need to be taken care for future development of the microinverter technology

Topology Studies and Control of Microinverters for Photovoltaic Applications

Ph.DDOCTOR OF PHILOSOPH