Magnetic Design and Experimental Evaluation of a Commercially Available Single Integrated Transformer in Three-Phase LLC Resonant Converter

• Published in: IEEE transactions on industry applications Vol. 54; no. 6; pp. 6190 - 6204
• Main Authors: Noah, Mostafa, Kimura, Shota, Imaoka, Jun, Martinez, Wilmar, Endo, Shun, Yamamoto, Masayoshi, Umetani, Kazuhiro
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Air gaps; Circuit design; Circuits; Computer simulation; Conduction losses; Cost analysis; DC/DC converter; Electric converters; Electric power distribution; Energy conversion; ferrite magnetic cores; Finite element method; Industrial applications; Legged locomotion; Magnetic cores; Magnetic flux; Magnetic properties; Magnetic resonance; Multiphase; Phase transitions; Power converters; Power loss; soft-switching converters; Thermal stress; three-phase LLC resonant converter; Topology; Transformer cores; transformer design; Transformers; Voltage converters (DC to DC); Weight
• ISSN: 0093-9994; 1939-9367
• DOI: 10.1109/TIA.2018.2856631

Multiphase topologies are preferably employed in power conversion systems to lessen the per-phase circuit current, conduction losses, devices thermal stresses, and to reduce the output current ripples. A multiphase LLC resonant dc/dc converter usually possesses a number of magnetic cores equal to the number of phases. These magnetic cores are the major contributors to supply volume, weight, and size. For these reasons, circuit designers tend to select the topologies that have a minimal number of magnetic cores. In this paper, the authors aim to promote the industrial applications of the three-phase LLC resonant converter by integrating three transformers into a single commercially available magnetic core to reduce the volume, weight, and cost of the power converter. A comprehensive magnetic analysis for the three-phase-integrated transformer is conducted. Finite element method (FEM) simulation and experimental tests are carried out to validate the proper operation of the integrated transformer utilized in a 390-/12-V to 500-W prototype. Furthermore, the power losses distribution has been presented. The proposed integrated transformer has been proven effective, and it realized a uniform thermal distribution along the core compared to the three-discrete transformers.