Modeling, impedance design, and efficiency analysis of quasi-Z source module in cascaded multilevel photovoltaic power system

Dongsen Sun, Baoming Ge, Xingyu Yan, Daqiang Bi, Hao Zhang, Yushan Liu, Haitham Abu-Rub, Lazhar Ben-Brahim, Fang Zheng Peng

Research output: Contribution to journalArticle

138 Citations (Scopus)


The quasi-Z source (qZS) cascaded multilevel inverter (CMI) (qZS-CMI) presents attractive advantages in application to photovoltaic (PV) power system. Each PV panel connects to an H-bridge qZS inverter (qZSI) to form a power generation module. The distributed maximum power point tracking and all modules' dc-link peak voltage balance can be achieved. However, it is the same with the conventional CMI that the second-harmonic (2ω) voltage and current ripples exist in each qZSI module. It is crucial for a qZS-CMI to design the reasonable qZS network parameters to limit the ripples within a desired range. This paper proposes an analytic model to accurately calculate the 2ω voltage and current ripples of each qZSI module. A qZS impedance design method based on the built model is proposed to limit the 2ω ripples of dc-link voltage and inductor current. Simulated and experimental results through using the designed 1.5-kW prototype validate the proposed analytic model and the design method. Furthermore, this paper analyzes all of the operating states for a qZSI module and calculates the power loss. The measured efficiency from the prototype verifies the theoretical calculation, and the qZS-CMI-based grid-tie PV power system is tested in practical.

Original languageEnglish
Article number6736062
Pages (from-to)6108-6117
Number of pages10
JournalIEEE Transactions on Industrial Electronics
Issue number11
Publication statusPublished - Nov 2014



  • Circuit modeling
  • multilevel inverter
  • photovoltaic (PV) power generation
  • quasi-Z source (qZS) inverter

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering

Cite this