LLC Resonant Converters for Energy Efficient Power Electronics Systems
Loading...
Authors
He, Binghui
Date
2024-07-03
Type
thesis
Language
eng
Keyword
LLC resonant converter , Wide voltage gain variation , Bidirectional operation , Electromagnetic interference
Alternative Title
Abstract
With modern power electronic systems advancing towards higher efficiency, smaller size, lighter weight, and lower noise, Switch-Mode Power Supplies (SMPSs) based on resonant converters have garnered widespread attention. Among various resonant converters, LLC resonant converters are extensively employed in today's most popular industry applications such as laptop/cellphone power adapters, data center power supplies, and EV (Electrical Vehicle) charging applications. This thesis addresses several challenges in LLC resonant converters, including wide voltage variation ranges, bidirectional operation, and Electro-Magnetic Interference (EMI) noise reduction. New technologies have been proposed to address these issues.
The LLC resonant converter faces limitations in voltage gain due to its constrained switching frequency, posing challenges in maintaining high efficiency across a wide voltage regulation range. To address this issue, a Power Cycle Modulation (PCM) control scheme is proposed for high-efficiency operation across wide input and output voltage ranges and load variations. Implemented with low-cost Microcontroller Units (MCUs), the PCM control method is also applicable to other resonant topologies and suitable for high-frequency operation.
While the forward operation of LLC resonant converters is well-studied, backward operation, crucial for bidirectional applications, lacks sufficient research. A double-loop control strategy is proposed to enhance the isolated LLC bidirectional converter's performance during backward operation. This strategy reduces double line-frequency ripple current and improves overall efficiency without additional costs, significantly lowering the Root Mean Square (RMS) current within the LLC converter system.
Reducing EMI emissions from power converters is crucial to enhance power density and minimize filter size. This thesis proposes effective noise reduction techniques for LLC converters, including Common-Mode (CM) noise cancellation capacitors for Half-Bridge (HB) LLC converters, two resonant branches with a sandwich transformer winding structure for Full-Bridge (FB) LLC converters, and the Split Primary Winding Transformer (SPWT) method with complementary couple-turns. These solutions improve CM noise performance, allowing for smaller CM EMI filters and enhancing system power density.
This thesis employs mathematical modeling, PSIM-based simulation, Finite Element Analysis (FEA), and experimental tests to verify the proposed theories and solutions.
Description
Citation
Publisher
License
Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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.
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.