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Arshadi, Sayed Abbas

University of British Columbia

Resonant power converters have gained popularity in many application, especially where there are strict requirements on efficiency, power density, and Electromagnetic Compability (EMC). Among different types of resonant converters, LLC and CLLC resonant converters have attracted more attention for uni-directional and bi-directional applications, respectively. This is due to the unique features of these types of converters, such as soft switching. Half-bridge and full-bridge resonant structures have are suitable for low to medium power levels, and three-phase structures are considered for higher power levels. Three-phase resonant converters provide high efficiency, low current ripple, good thermal distribution, and small filter and heat sink size (high power density), that makes them an attractive option for high power battery charger applications. Although there has been substantial research and development on single-phase LLC and CLLC resonant converters for low to medium power levels, the literature investigating three-phase structures has been very limited. Issues to be investigated for three phase resonant converters are: 1) passive components tolerances, which leads to unbalanced behavior of the converter, 2) development of a balancing technique to mitigate the unbalanced behavior of the converter, 3) the natural limited gain range of resonant converter structure, 4) poor light load efficiency of the three-phase resonant converter and possible phase shedding strategies to improve it, and also to increase the reliability of the system. In this work, methods to use three-phase LLC and CLLC resonant converters more efficiently are investigated. This includes: 1) investigation of imbalances in three-phase LLC converters and proposing a novel strategy referred to as Trigonometric Current Balancing (TCB) technique to mitigate the unbalanced behavior of the converter under sever unbalanced situation, 2) investigating phase-shedding techniques and strategies to improve the operation of the converter at light load conditions and extend the gain range of the converter, and 3) investigating the behavior of the three-phase CLLC resonant converter for bi-directional power applications.

Text

2022-11-21

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/83166

Electrical and Computer Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/