Optimal Design of Megahertz $LLC$ Converter for 48-V Bus Converter Application

Journal Article · Wed Sep 04 00:00:00 EDT 2019 · IEEE Journal of Emerging and Selected Topics in Power Electronics

DOI:https://doi.org/10.1109/jestpe.2019.2939469· OSTI ID:1799217

Cai, Yinsong ^[1]; Ahmed, Mohamed H. ^[2]; Li, Qiang ^[2]; Lee, Fred C. ^[2]

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1. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); OSTI
2. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

Intermediate bus architecture employing 48-V bus converters is widely used in power supply applications. With the rapid increase of demanded power by these loads, higher efficiency and power density are driving better performance power management solutions. In this article, a Gallium Nitride (GaN) based design of a two-stage solution is proposed. The first stage is a multi-phase Buck for regulation. The second stage is an LLC converter with a fixed switching frequency for isolation. The detailed design and optimization of the LLC converter are studied. To achieve high power density and high efficiency, the transformer design becomes critical at megahertz frequency. The matrix transformer concept is applied and a merged winding structure is used for flux cancellation, which effectively reduces the ac winding losses. A novel primary termination and via structure is proposed, resulting in a great loss reduction. In addition, to study the current sharing of parallel winding layers, a 1-D analytic model is proposed, and a symmetrical winding layer scheme is used to balance the current distribution. Finally, the prototype for the two-stage bus converter is developed, with a peak efficiency of 96% and a power density of 615 W/in ³ .

• Research Organization: North Carolina State Univ., Raleigh, NC (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• Grant/Contract Number: EE0006521
• OSTI ID: 1799217
• Journal Information: IEEE Journal of Emerging and Selected Topics in Power Electronics, Journal Name: IEEE Journal of Emerging and Selected Topics in Power Electronics Journal Issue: 1 Vol. 8; ISSN 2168-6777
• Publisher: IEEE
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
density measurement
power electronics
power system measurements
switching frequency
transformer cores
transmission line matrix methods
windings