Bidirectional DC-DC Converter with Direct Power Transfer Capability for Battery Charging Applications
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Authors
Goudarzitaemeh, Sajjad
Date
2024-11-12
Type
thesis
Language
eng
Keyword
Bidirectional DC-DC Converter , Direct Power Transfer , Dual Active Bridge Converter , Nonlinear Geometric SO(2) Controller , Battery Chargers
Alternative Title
Abstract
Conventional bidirectional DC-DC converters face challenges in applications with a wide range of operating conditions, such as energy storage systems. Variations in operating points often lead to sub-optimal performance and excessive conduction and switching losses. This thesis introduces a novel bidirectional DC-DC converter with Direct Power Transfer (DPT) capability to address these issues. The proposed converter transfers a significant portion of power via magnetic coupling, reducing the power processing burden through power semiconductors and passive components. Additionally, it utilizes an inherent soft-switching feature that minimizes switching losses. Together, these innovations enhance overall efficiency across a broad range of operating conditions.
To further mitigate conduction losses, the converter incorporates an integrated coupled inductor in series with the transformer, which shapes the high-frequency current waveform to reduce current stress on power semiconductors. The extended phase-shift modulation technique enables precise control of instantaneous power flow and extends the range of soft switching over wide voltage variations.
To optimize high-frequency current shaping, a multilevel version of the DC-DC converter with DPT capability is also proposed. This multilevel structure supports a new modulation scheme that reduces peak and RMS current values, improving efficiency. Both theoretical and experimental results demonstrate the superior performance of this topology.
Linear controllers impose many limitations on the performance of the DC-DC converters. Commonly, the dynamics of DC-DC converters are averaged over one switching cycle and then linearized to achieve a Linear Time-Invariant system model for the controller design. The linear approximation of nonlinear systems around a single operating point and averaging would result in sub-optimal performance of DC-DC converter, particularly in applications with wide range of operating conditions. To overcome these limitations, a nonlinear geometric-based SO(2) controller is proposed, which can directly control the high-frequency current. The system trajectory for the proposed converter evolves on a surface of a torus, which is a Lie group. Thus, the proposed SO(2) controller is designed on the respective Lie algebra to achieve a fast dynamic response and improved stability. The analysis, simulation and experimental results demonstrate the superior performance of the proposed controller.
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-ShareAlike 4.0 International
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial-ShareAlike 4.0 International