Abstract
With the continuous development of new energy, there is more and more research on step-up inverters in photovoltaic and wind power generation systems. The Z-source inverter has become a research hotspot because of its small output THD (Total Harmonic Distortion) and high reliability. However, the traditional Z-source inverters cannot meet the higher boost requirements of new energy power generation. The quasi-z-source inverter with stronger boosting ability came into being. The high step-up Z-source inverters presented in existing literature is only focused on one or several topologies and lacks a comparative analysis on different topologies. Based on the quasi-Z-source inverter, this paper proposes a family of quasi-z-source inverters with a coupled inductor. The required voltage gain can be obtained by changing the turns ratio of the coupled inductor, which provides a new control variable for the system and makes the design of the system becomes more flexible. Through the analysis and comparison of each topology in terms of boost capacity, voltage stress, coupled inductor volume, circuit efficiency, and input ripple, the characteristics of each topology are summarized. The representative topology was simulated and analyzed, and a 1 kVA prototype was developed in the laboratory to verify the correctness of the theoretical analysis.
Highlights
With the rapid development of new energy generation systems, modern power electronics technology has become an important issue
The coupled inductor of class D acquires the least weight and volume, no average current is flowing through class D coupled inductor as compared to the first three CI-quasi-Z-source inverter (qZSI) topologies
The filtering inductors of these eight topologies can be divided to four kinds, but they are opposite to the volume of coupled inductors
Summary
With the rapid development of new energy generation systems, modern power electronics technology has become an important issue. Compared to traditional ZSI, the quasi-Z-source inverter (qZSI) has the advantages of the common inverter bridge and power supply, lower capacitor voltage stress, continuous input current, etc. Both ZSI and qZSI show a low voltage boosting capability and cannot meet the requirement of high voltage ratio. The proposed inverter is composed of a coupled inductor and a voltage multiplier, which can achieve the required high voltage gain with high efficiency and operating under wide input voltage range. The characteristics of various topologies are compared and analyzed, including the voltage stress of capacitors and diodes, output current ripple, the size of the coupled inductor, and circuit efficiency.
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