Boost-type common-ground PV inverter based on quasi-Z-source and switched-capacitor. (January 2023)

• Record Type: Journal Article
• Authors: Ye, Yuanmao; Chen, Minhao; Wang, Xiaolin; Cao, Lingling
• Is Part Of: International journal of electrical power & energy systems. Volume 144(2023)
• Publication Date: 2023-01
• Subjects: PV inverter -- Common-ground -- Boost-type -- Switched-capacitor -- Quasi-Z-source; Electrical engineering -- Periodicals; Electric power systems -- Periodicals; Électrotechnique -- Périodiques; Réseaux électriques (Énergie) -- Périodiques; Electric power systems; Electrical engineering; Periodicals; 621.3
• DOI: 10.1016/j.ijepes.2022.108522
• Languages: English
• ISSNs: 0142-0615

Abstract

Highlights: A new boost-type common-ground PV inverter is developed by using a front-side quasi-Z-source unit to feed a switched-capacitor-based inverting circuit. The problem of inrush charging current of capacitors is successfully solved in the new PV inverter. The enhanced boost capability can be adjusted by controlling the duty ratio of shoot-through states. The input current is continuous, because the input source is always connected in series with an inductor. All switching devices used in the proposed PV inverter are rated at the same voltage. Abstract: Common-ground type of transformerless photovoltaic (PV) inverters is an effective means to eliminate common-mode leakage current. Recent years, switched-capacitor (SC) technique with the advantage of voltage boosting has been successfully used in this field. In order to inherit the merits of SC-based common-ground PV inverters, and to further improve the performance in the aspects of inrush charging current, input current quality and boost capability of SCs, a new boost-type common-ground (BCG) inverter is developed by inserting a quasi-Z-source (qZS) unit in an SC-based common-ground inverter. Specifically, an SC unit employed in the BCG inverter is fed by the qZS circuit rather than a voltage source, so that the inrush charging current is effectively limited by inductors of the qZS unit. Meanwhile, the boost capacity is further improved and the input current has been continuous. Both circuit configurations of single-phase and three-phase as well as their operation principle and modulation are analyzed in detail. Especially in the three-phase configuration, only one qZS unit is used to feed three SC units and the input current is almost constant. The feasibility of the proposed BCG inverter is experimentally verified by a downscale three-phase prototype.