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This paper presents a 3−kW400−V/48−V LLC converter for 48−V auxiliary power architectures in electric vehicles and other high-current low-voltage platforms. The main design issue is the magnetic stage, which must support an 8:1 step-down ratio and more than 60 A on the low-voltage side without excessive AC winding loss or large magnetic volume. To address this issue, a High- Q Litz Planar Transformer (HLPT) is proposed. The transformer uses a multi-layer interleaved Litzwire layout to reduce proximity-effect loss at 200 kHz, and its controlled leakage inductance is directly used as the LLC resonant inductance so that no extra resonant inductor is required. A 3-kW prototype verifies the design. The measured peak efficiency is 97.2%, and the full-load efficiency is 96.5%. The measured loss breakdown shows that transformer winding loss is kept below 20% of the total loss, which confirms the value of the proposed integrated magnetic design for compact 48−V power conversion.
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High-Frequency Accurate Dual-Side Equivalent Circuit Model for Transformers
This study delves into the modeling of a transformer in the frequency range of 100 KHz to 30 MHZ. The coupling coefficient was considered as a function of leakage and self-inductance and incorporated in the optimization process of transformer modeling in the proposed method. The equivalent circuit focused on the critical aspects of leakage inductance, parasitic capacitance, and winding effects. At first, the winding effect of an air-core inductor over wide frequency range with both single-layer and double-layer windings was shown. Then an equivalent circuit was proposed to model a transformer over this frequency range. The comparison between the measured and proposed model demonstrates strong accuracy over the frequency range, with an average relative error of 2.2% on the primary side and 6% on the secondary side.
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- Award ID(s):
- 1916535
- PAR ID:
- 10696608
- Publisher / Repository:
- IEEE
- Date Published:
- ISBN:
- 979-8-3503-8972-2
- Page Range / eLocation ID:
- 225 to 228
- Subject(s) / Keyword(s):
- Couplings Accuracy Atmospheric modeling Windings Transformers Vectors Frequency measurement Integrated circuit modeling Optimization Equivalent circuits Accuracy Of Model Equivalent Circuit Equivalent Circuit Model Frequency Range Coupling Coefficient Transformer Model Parasitic Capacitance Wind Events Primary Side Secondary Side Average Relative Error Leakage Inductance Impedance Higher Frequency Measurement Data Frequency Band Resonance Frequency Simulated Annealing Power Electronics Total Flux Advanced Design System Vector Network Analyzer Leakage Flux Electromagnetic Compatibility Turns Ratio Extra Loop SMA Connector Simulated Annealing Optimization Main Resonance Equivalent circuit coupling coefficient optimization transformer modeling winding effect
- Format(s):
- Medium: X
- Location:
- Taipei, Taiwan
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Conference Paper:
- https://doi.org/10.1109/APEMC62958.2025.11051499
