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Design and Analysis of a Three-Phase High-Frequency Transformer for Three-Phase Bidirectional Isolated DC-DC Converter Using Superposition Theorem-by Yasir S. Dira ,Ahmad Q. Ramli ,Nadia M. L. Tan,and Giampaolo Buticchi Institute of Power Engineering, Universiti Tenaga Nasional, Kajang 43000, Malaysia; yasirsabah291@gmail.com (Y.S.D.); qisti@uniten.edu.my (A.Q.R.) 2 Key Laboratory of More Electric Aircraft Technology of Zhejiang Province, University of Nottingham Ningbo China, Ningbo 315100, China
Abstract: Battery energy storage systems based on bidirectional isolated DC-DC converters (BIDCs)
have been employed to level the output power of intermittent renewable energy generators and
to supply power to electric vehicles. Moreover, BIDCs use high-frequency transformers (HFTs) to
achieve voltage matching and galvanic isolation. Various studies have recently been conducted using
soft magnetic materials, such as nanocrystalline, amorphous solids, and ferrite, to develop more
compact and effective transformers with superior power densities. The HFTs in three-phase BIDCs
are composed of three magnetic cores. However, this leads to low power density and high cost.
Besides, the three-phase (3P) ferrite core has not been investigated for high-power converters such
as 3P-BIDCs. This paper presents the design and development of a 3P-EE ferrite magnetic core for
3P-BIDCs. The area product design method was used to determine the core and winding design. The
paper also proposes the use of the superposition theorem in conducting a magnetic circuit analysis
to predict the flux density and magnetising inductance of the transformer core. Moreover, the use
of the superposition theorem allowed the required air-gap length for balancing the distribution of
flux density and magnetizing inductance in the transformer core to be determined. The balanced
flux distribution and magnetizing inductance resulted in a uniform core loss and temperature in the
transformer. This paper also presents the experimental results of the designed HFT operated in a
300-V, 3-kW 3P-BIDC. The experimental results showed that the proposed HFT achieved a balanced
flux density and magnetizing inductance with a high power density and low cost. Moreover, the
transformer performed at a maximum efficiency of 98.67%, with a decrease of 3.33 ◦C in the overall
temperature of the transformer as compared to the transformer without air gaps.
VIEW FULL TEXT: https://www.mdpi.com/2071-1050/16/21/9227
