Triangular/trapezoidal current mode for high step ratio modular multilevel dc-dc converter
Publication Date
December 13, 2022
Creator
Abstract
Recent developments in dc powered technologies have increased interest in highly efficient dc-dc converters, especially at high voltage and high-step voltage ratios. Modular multilevel converters (MMCs) are an attractive alternative approach to this demand because they can manage medium and high dc voltages while using standard semiconductor devices with high efficiency if they employ soft-switching techniques. However, the latest soft-switching techniques proposed to MMCs require resonant circuits, limiting their operation.
This thesis proposes a new zero-current switching modulation technique for a high-step-ratio MMC dc-dc converter without resonant circuits. The proposed modulation generates a trapezoidal or triangular current as result of a rms current minimization problem. The proposal enables the soft-switching operation of the converter over a wide output voltage and power range, using a simple control scheme to regulate the output voltage and the voltage balance among the floating cell capacitors.
The effectiveness of the proposed control strategy is validated through simulations and experimental results. Simulation results are obtained for a 1MW, 10kV to 1kV converter model developed in PLECS software. Additionally,
a 1 kVA downscale prototype has been designed and constructed during this Ph.D.
Simulation and experimental results for steady-state, bidirectional power-flow, and input voltage and load disturbances have confirmed the successful operation of the triangular/trapezoidal current mode. In all the experiments, the proposed control systems ensure proper capacitor voltage balancing, proving that the converter has satisfactory dynamic response and cell voltage balance over a wide output voltage and power range.
Item Type
ethesis
Thesis Type
PhD
Supervisors
Pereda, Javier
Subjects (LC)
Associated Schools / Departments
Department of Electrical and Electronic Engineering (UK)
eprints ID
69731
UoN Repository URI
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UoN_PUC_Thesis_CPINEDA.pdf
Type
Full-text
Description
Examined. PhD. Thesis Final Version
Size
25.75 MB
Format
Adobe PDF
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