Front-End Isolated Quasi-Z-Source DC–DC Converter Modules in Series for High-Power Photovoltaic Systems—Part II: Control, Dynamic Model, and Downscaled Verification

• Published in: IEEE transactions on industrial electronics (1982) Vol. 64; no. 1; pp. 359 - 368
• Main Authors: Liu, Yushan, Abu-Rub, Haitham, Ge, Baoming
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Computational modeling; DC-DC power converters; DC–DC power conversion; Dynamic models; Electric bridges; galvanic isolation; Inverters; Maximum power point trackers; Modular structures; Modular systems; Modulation; Photovoltaic cells; photovoltaic power system; quasi-Z-source converter; Regulators; Voltage control; Voltage converters (DC to DC)
• ISSN: 0278-0046; 1557-9948
• DOI: 10.1109/TIE.2016.2598675

This paper is the continuation of Part I in which a quasi-Z-source modular cascaded converter (qZS-MCC), comprising front-end isolated qZS half-bridge dc-dc converter submodules (SMs), for dc integration of high-power photovoltaic (PV) systems is proposed. The qZS-MCC-based PV system features modular structure, high-voltage dc collection of PV power, simple control with a unified and constant duty cycle for the front-end isolation converter of all SMs, and low qZS impedance due to no double-line-frequency pulsating power. Here, control scheme of the qZS-MCC PV system integrated into the dc collection grid is investigated. Dynamic model of the system is established for controllers design and time-domain transient simulation. Experimental tests are carried out on the downscaled prototype as a proof-of-concept of the proposed control and modeling, demonstrating the validity of the proposed approaches.