Parallel PV Configuration with Magnetic-Free Switched Capacitor Module-Level Converters for Partial Shading Conditions

Georgios Kampitsis, Efstratios Batzelis, Remco van Erp and Elison Matioli
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Georgios Kampitsis: Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ, UK
Efstratios Batzelis: Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ, UK
Remco van Erp: Power and Wide-Band-Gap Electronics Research Laboratory, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
Elison Matioli: Power and Wide-Band-Gap Electronics Research Laboratory, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

Energies, 2021, vol. 14, issue 2, 1-17

Abstract: In this paper, a module-level photovoltaic (PV) architecture in parallel configuration is introduced for maximum power extraction, under partial shading (PS) conditions. For the first time, a non-regulated switched capacitor (SC) nX converter is a used at the PV-side conversion stage, whose purpose is just to multiply the PV voltage by a fixed ratio and accordingly reduce the input current. All the control functions, including the maximum power point tracking, are transferred to the grid-side inverter. The voltage-multiplied PV modules (VMPVs) are connected in parallel to a common DC-bus, which offers expandability to the system and eliminates the PS issues of a typical string architecture. The advantage of the proposed approach is that the PV-side converter is relieved of bulky capacitors, filters, controllers and voltage/current sensors, allowing for a more compact and efficient conversion stage, compared to conventional per-module systems, such as microinverters. The proposed configuration was initially simulated in a 5 kW residential PV system and compared against conventional PV arrangements. For the experimental validation, a 10X Gallium Nitride (GaN) converter prototype was developed with a flat conversion efficiency of 96.3% throughout the power range. This is particularly advantageous, given the power production variability of PV generators. Subsequently, the VMPV architecture was tested on a two-module 500 W P prototype, exhibiting an excellent power extraction efficiency of over 99.7% under PS conditions and minimal DC-bus voltage variation of 3%, leading to a higher total system efficiency compared to most state-of-the-art configurations.

Keywords: gallium nitride; magnetic-free converters; module-level converters; parallel architecture; partial shading; photovoltaic systems; switched capacitor converters (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
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