A Novel Dual-Input High-Gain Transformerless Multilevel Single-Phase Microinverter for PV Systems

This article proposes a novel single-phase microinverter that is fit to process the power of two photovoltaic (PV) modules in a modular way. The proposed topology combines a full-bridge inverter integrated with two dc-dc boost converters, in addition to a dc link that consists of switched capacitor (SC) networks. The operating modes of the proposed topology are illustrated. The voltage stress of all components is identified. A modulation technique along with a control system is developed for a proper operation of the proposed topology. A comparative study with other topologies is introduced, and the following merits for the proposed one are presented: 1) The power of two PV modules can be harvested individually or simultaneously without any circulating current issues; 2) very high gain can be acquired, and, thus, no series connection of PV modules is required for grid-tied applications; 3) transformerless operation; 4) multilevel shaping of the output voltage, and, thus, reduced filter size is required; and 5) self-balancing for the dc-link capacitors, and, thus, simple control systems can be used. The performance of the seven-level version of the proposed topology is validated using real-time simulation and experimental prototype under grid-tied and stand-alone conditions, respectively.