Modeling and design of an LLC resonant converter for a wide voltage conversion ratio applications

Maheshwari, Anuj

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https://hdl.handle.net/2142/117842 Copy

Description

Title

Modeling and design of an LLC resonant converter for a wide voltage conversion ratio applications

Author(s)

Maheshwari, Anuj

Issue Date

2022-12-09

Director of Research (if dissertation) or Advisor (if thesis)

Banerjee, Arijit

Department of Study

Electrical & Computer Eng

Discipline

Electrical & Computer Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

LLC resonant converter, wide-output range, efficiency, power density, state-plane analysis

Abstract

LLC Resonant converters provide soft-switching capabilities enabling high switching frequencies and high efficiency. A low-quality factor design operating below resonant frequency is preferred for wide voltage-gain applications to reduce the required range of operating frequencies. Phase-shift modulation can be used in conjunction with frequency modulation to further narrow the operating frequency range. A first harmonic analysis-based approach has high inaccuracies in estimating capacitor voltage, inductor current, and voltage gain, which are critical parameters to design the converter and estimate the losses when phase-shift modulation is employed. This thesis presents a state-plane-based modeling framework to accurately analyze the converter when both frequency and phase-shift modulation are used. The proposed model is then used to highlight the power density versus efficiency trade-off obtained by utilizing phase shift as an additional control variable for an electric vehicle battery charging application. The accuracy of the model is verified by experiments on a 10kW SiC-based prototype. Two converters are designed using the trade-off curve, one employing only frequency modulation and the other using both frequency and phase-shift modulation. These two converters achieve the same efficiency over the constant current battery charging mode but, the addition of phase-shift modulation reduces the transformer’s size by 22% and its weight by 28%.

Graduation Semester

2022-12

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Anuj Maheshwari

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