Switched Z-Source/Quasi-Z-Source DC-DC Converters With Reduced Passive Components for Photovoltaic Systems

IEEE Access

Junfeng Liu¹  Jianyong Qiu¹  Jun Zeng²  Jialei Wu² 

[1] College of Automation Science and Engineering, South China University of Technology, Guangzhou, China;New Energy Research Centre, South China University of Technology, Guangzhou, China;

关键词: PV systems;    switched Z-source/quasi-Z-source;    dc-dc converters;    reduced passive components;   

DOI  :  10.1109/ACCESS.2019.2907300

来源: DOAJ

【 摘 要 】

In this paper, switched Z-source/quasi-Z-source dc-dc converters (SZSC/SQZSCs) are proposed for the photovoltaic (PV) grid-connected power system, where the high step-up dc-dc converters are required to boost the low voltage to high voltage. The boost factor is increased by adding another one switch and diode to the output terminals of traditional Z-source/quasi-Z-source dc-dc converters. Not only does the output capacitor function as the filter capacitor; it is also connected in series into the inductors' charging loops when both switches are turned on. Compared with existing Z-source based structures, higher boost factor is realized through a small duty cycle (smaller than 0.25). On the one hand, the instability caused by the saturation of the inductors can be avoided. On the other hand, a larger range can be reserved for the modulation index of the backend H-bridge when they are used for the dc-ac conversion. Moreover, much fewer passive components are employed when compared with the recently proposed hybrid 3-Z-network topologies that have the same voltage gain, which can enhance the power density and decrease the cost. The performances of the proposed converters, including their operational principles in continuous and discontinuous current modes, voltage and current parameters of components, and impacts of parasitic parameters, are analyzed. The simulation and experimental results are given to verify the aforementioned characteristics and theoretical analysis.

【 授权许可】

Unknown