Overcoming thermal-spatial constraints in server power supplies: immersion-cooled 54 V modular design achieving threefold power density enhancement and titanium class efficiency

High-efficiency, high-power-density, and compact server power supplies are critical for next-generation sustainable data centers. However, conventional 12 V air-cooled power supplies face substantial challenges due to high current density, inadequate thermal dissipation, and complex power distribution networks. These situations restrict power density scaling and alter the conversion efficiency. In this study, a novel 54 V modular power supply integrated with single-phase immersion cooling is used to substantial improve the thermal performance and enable ultracompact integration, thus achieving high efficiency and power density. A two-stage power conversion topology, which comprises an interleaved totem pole power factor correction (PFC) rectifier, is also used to improve the power factor and suppress harmonics. A full-bridge Inductor-Inductor-Capacitor (LLC) resonant converter employs soft-switching techniques to minimize switching losses. Furthermore, immersion cooling with a dielectric fluid is implemented to achieve superior thermal performance via directcontact heat transfer, thereby eliminating the use of fans and offering exceptional heat removal efficiency alongside optimized thermofluidic integration. Experimental validation under extreme conditions (50 °C ambient, 90–230 V AC input, 80% to 100% load) demonstrated an ultrahigh power density of 64.36 W/inch³ in a 1U form factor. The performance is three times greater than that of conventional air-cooled systems (21.15 W/inch³). The proposed prototype achieves maximum efficiencies of 96.39% (DC input) and 96.24% (AC input), exceeding the 80 Plus Titanium standards. Moreover, the critical MOSFET temperature remains at 98.5 ± 1.2 °C within a safety margin of 21.5 °C while achieving a near-unity power factor (99.97% at full load). The current total harmonic distortion is maintained within the Titanium specifications under all operating conditions.

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Cite this article

[IEEE Style]

L. Guo, J. Liu, L. Chen, G. Li, W. Zhou, J. Zou, "Overcoming thermal-spatial constraints in server power supplies: immersion-cooled 54 V modular design achieving threefold power density enhancement and titanium class efficiency," Journal of Power Electronics, vol. 26, no. 3, pp. 658-669, 2026. DOI: 10.1007/s43236-025-01263-3.

[ACM Style]

Liwen Guo, Jing Liu, Liang Chen, Guolong Li, Wenfei Zhou, and Jianxiao Zou. 2026. Overcoming thermal-spatial constraints in server power supplies: immersion-cooled 54 V modular design achieving threefold power density enhancement and titanium class efficiency. Journal of Power Electronics, 26, 3, (2026), 658-669. DOI: 10.1007/s43236-025-01263-3.