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High Frequency High Boost Ratio Dc-dc Converters with Wide Bandgap Devices for PV System Applications

Li, Cong
http://rave.ohiolink.edu/etdc/view?acc_num=osu1411858489

Abstract Details

2014, Doctor of Philosophy, Ohio State University, Electrical and Computer Engineering.
In the past decades, low voltage dc energy sources, such as solar photovoltaic (PV) panels, fuel cells, batteries and ultra-capacitors, have seen increasing applications in the energy supply area. Due to their low voltage ratings, those dc energy sources are commonly placed in series to reach required voltage levels for post stage power conversion equipment. However, inherently, placing those dc energy sources in series will introduce problems, such as reduced generation capability and lower reliability. In order to solve these problems, this dissertation presents solutions to utilize these dc energy sources in parallel. This dissertation first proposes a design target which requires a 50 times boost ratio to enable practical implementation of parallel connected PV panels. Then, a review of existing high boost ratio dc-dc circuit topologies is carried out in Chapter 2, and five basic voltage boosting techniques are extracted from existing circuits. With these extracted techniques, different circuit topologies can be classified and compared, which makes it convenient to investigate the main characteristics of each circuit. Furthermore, in order to carry out a quantitative evaluation of existing circuit topologies, several selection criteria of dc-dc converters (SCODCs) are proposed in Chapter 3. With these SCODCs, quantitative power requirements on the switches, capacitors and magnetic components of different dc-dc circuits can be obtained, which makes comparison studies among different circuits more intuitive. Quantitative comparison studies among five circuit examples show that those existing circuit candidates are not suitable for high boost ratio and high power requirements due to different reasons, including complicated circuit structures, large power requirements on the switches or passive components which will potentially lead to low efficiencies, and difficulties in high frequency applications. Therefore, improvements on existing topologies are needed to provide acceptable solutions for the design targets, which are the main topics of Chapter 4 and Chapter 5. Chapter 4 focuses on solving common problems of high boost ratio resonant converters, such as large power requirements on the passive components, and high circulating current at light load conditions. Adaptive inductor is discussed as a possible way to decrease the system size and increase system efficiency. Chapter 5 proposes a family of switched capacitor-inductor (C-L) circuits which is largely based on parallel charging serial discharging technique. A comparison of the two solutions proposed in Chapter 4 and 5 shows that the solution in Chapter 5 is more feasible with available materials and existing technologies. Therefore, a 1.2 kW lab prototype, with an input voltage ranges between 20 V and 40 V and a constant output voltage at 1000 V was built and tested. During the tests, the switching frequency was set at 187.5 kHz. Experimental results have validated the proposed circuit topology and demonstrated a 96.1% peak efficiency and an overall efficiency over 94.5%.
Jin Wang (Advisor)
188 p.
Electrical Engineering

Recommended Citations

Citations

  • Li, C. (2014). High Frequency High Boost Ratio Dc-dc Converters with Wide Bandgap Devices for PV System Applications [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1411858489

    APA Style (7th edition)

  • Li, Cong. High Frequency High Boost Ratio Dc-dc Converters with Wide Bandgap Devices for PV System Applications. 2014. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1411858489.

    MLA Style (8th edition)

  • Li, Cong. "High Frequency High Boost Ratio Dc-dc Converters with Wide Bandgap Devices for PV System Applications." Doctoral dissertation, Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1411858489

    Chicago Manual of Style (17th edition)

osu1411858489
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This open access ETD is published by The Ohio State University and OhioLINK.