Date of Award
2025
Degree Type
Dissertation
Degree Name
Doctor of Philosophy in Electrical Engineering
Department
Electrical, Computer, and Biomedical Engineering
First Advisor
Yeonho Jeong
Abstract
Electric mobility is now widely adopted to reduce reliance on fossil fuels and lower emissions. A power conversion system, also known as a switching-mode power supply, comprising a converter and its energy management scheme, is always required between the energy sources and the load to regulate voltage levels and control energy flow by turning switches on or off to store or release the energy of the inductors and capacitors. To overcome the limitation of using batteries alone, integrating a fuel cell (FC) with additional energy storage systems (ESSs) forms a hybrid architecture that can provide longer operation time. For the design of the converter in such systems, an integrated multi-input-single-output (MISO) converter is preferred due to its fewer components compared to paralleled single-input-single-output (SISO) converters. However, two challenges arise in such systems due to their integrated feature: 1) mixed energy flow and 2) limited scalability for adding new energy sources. Mixed energy flow complicates the energy management design since energy from different sources shares the same inductors or capacitors, making it difficult to regulate each source's energy. Limited scalability stems from the fact that, unlike SISO systems, where an additional source can be integrated simply by adding another SISO converter in parallel, expanding an MISO converter requires redesigning the power stage and its control to accommodate extra inputs, which restricts its adaptability to varying operating conditions and application requirements.
In this dissertation, a new MISO converter is proposed by leveraging the structural characteristics of two commonly used SISO converters, the buck and boost converters. It will be first presented with its simple structure, operating principles, and design guidelines. Building on an initial proportional-integral (PI)-based control effort that addressed mixed energy flow but required intricate controller design and offered limited protection of FC endurance, a refined two-level energy management strategy is then developed. Using a dual-layer model predictive control (MPC) method, this strategy resolves the mixed energy flow without compensators while ensuring the long-term durability of the FC system. To address the limited scalability of conventional MISO converters, this work introduces extendable legs (ELs) that interface individual ESSs. These ELs can be paralleled and attached to the main converter without redesigning the power stage, while the corresponding energy management method is systematically extended from the previous PI-based scheme to accommodate additional sources. The effectiveness of the proposed converter and control was validated by an unmanned aerial vehicle (UAV) system with a 450 W FC, a 39.6-50.4 V Lithium Polymer battery, a 160 V 5 F supercapacitor as ESSs, and 16.8 V, 400 W motor loads.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Zhang, Xueshen, "HIGH POWER DENSITY CONVERTER WITH COORDINATED ENERGY MANAGEMENT FOR FLEXIBLE ENERGY STORAGE SYSTEM (ESS) INTEGRATION IN HYBRID E-MOBILITY" (2025). Open Access Dissertations. Paper 4533.
https://digitalcommons.uri.edu/oa_diss/4533