Classification of Three-Phase Grid-Tied Microinverters in Photovoltaic Applications

Abstract

Microinverters are an essential part of the photovoltaic (PV) industry with significant exponential prevalence in new PV module architectures. However, electrolyte capacitors used to decouple double line frequency make the single-phase microinverters topologies the slightest unit in this promising industry. Three-phase microinverter topologies are the new trend in this industry because they do not have double-line frequency problems and they do not need the use of electrolyte capacitors. Moreover, these topologies can provide additional features such as four-wire operation. This paper presents a detailed discussion of the strong points of three-phase microinverters compared to single-phase counterparts. The developed topologies of three-phase microinverters are presented and evaluated based on a new classification based on the simplest topologies among dozens of existing inverters. Moreover, the paper considers the required standardized features of PV, grid, and the microinverter topology. These features have been classified as mandatory and essential. Examples of the considered features for classifications are Distributed Maximum Power Point Tracking (DMPPT), voltage boosting gain, and four-wire operation. The developed classification is used to identify the merits and demerits of the classified inverter topologies. Finally, a recommendation is given based on the classified features, chosen inverter topologies, and associated features.

Single-Stage Three-Phase Grid-Tied Isolated SEPIC-Based Differential Inverter With Improved Control and Selective Harmonic Compensation

“…The fast penetration of RES, such as Photovoltaics (PVs), increases the popularity of DC-AC power converters at gridconnected applications [1][2][3][4][5]. However, the new PV architectures have independent PV modules with low input voltages [6][7][8][9]. Moreover, the partial shading scenarios force this voltage to be time-variant [8,10].…”

“…However, the new PV architectures have independent PV modules with low input voltages [6][7][8][9]. Moreover, the partial shading scenarios force this voltage to be time-variant [8,10]. This characteristic makes the traditional VSI and CSI have some limitations due to voltage gain property because VSI and CSI are a buck and boost inverter topologies, respectively [3,[8][9][10].…”

“…Moreover, the partial shading scenarios force this voltage to be time-variant [8,10]. This characteristic makes the traditional VSI and CSI have some limitations due to voltage gain property because VSI and CSI are a buck and boost inverter topologies, respectively [3,[8][9][10]. Therefore, inverter topologies with buck/boost features are the modern PV architectures trend with additional functionalities such as voltage isolation, modularity, scalability, and bi-directional power capability [8,10].…”

“…The issues related to leakage current and grid-operators safety have been increased. Isolated topologies are recommended to cut the leakage currents, decrease CMV, and EMI to maintain human safety [8,10]. Also, defining the number of connected PV modules with the utilized inverter topology needs a modular inverter to increase the system's flexibility and optimize it for further extension in the future [8].…”

“…Isolated topologies are recommended to cut the leakage currents, decrease CMV, and EMI to maintain human safety [8,10]. Also, defining the number of connected PV modules with the utilized inverter topology needs a modular inverter to increase the system's flexibility and optimize it for further extension in the future [8]. Furthermore, increasing the battery systems at the current utility grids, especially the advanced Electric Vehicles (EVs) and charging/discharging stations, put a new direction by optimizing DC-AC inverters with bi-directional power competence [11,12].…”