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This article proposes a matrix auto-transformer switched-capacitor dc–dc converter to achieve a high voltage conversion ratio, high efficiency, and high power density for 48-V data-center applications. On the high-voltage side, the proposed converter can fully leverage the benefits of high-performance low voltage stress devices similar to the multilevel modular switched-capacitor converter. Compared with the traditional isolated LLC converter with a matrix transformer, the proposed solution utilized a matrix autotransformer concept with merged primary and secondary side windings, thus leading to reduced transformer winding loss. The resonant inductor could be integrated into the transformer similar to the LLC converter. Because of the matrix autotransformer design, it can achieve a current doubler rectifier on the low voltage side. For less than 8-V low output voltage application, the current doubler rectifier design can fully utilize the best figure-of-merit 25-V device, which is more efficient than the full-bridge rectifier solution using two 25-V devices during the operation. All the devices can achieve zero voltage switching or zero current switching and can be naturally clamped without additional clamping circuits. A 500-W 48-V to 6-V dc–dc converter hardware prototype has been developed with optimized device selection and integrated matrix autotransformer design. Both simulation and experiment results have been provided to validate the features and benefits of the proposed converter. The maximum efficiency of the proposed converter can reach 98.33%.
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This content will become publicly available on June 10, 2027
A 3-kW 400-to-48-V LLC Converter with High- Q Integrated Litz Planar Transformer for 48-V Power Architectures
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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- PAR ID:
- 10703176
- Publisher / Repository:
- IEEE
- Date Published:
- ISBN:
- 979-8-3315-8773-4
- Page Range / eLocation ID:
- 1 to 6
- Format(s):
- Medium: X
- Location:
- Novi, MI, USA
- Sponsoring Org:
- National Science Foundation
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