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Achieving high efficiency and high power density features of intermediate bus converter (IBC) in data center application is very critical. This paper proposes a nonisolated switched-tank dc–dc converter (STC) to meet the high requirement of IBC. The proposed STC has fixed voltage conversion ratio. Theoretical analysis provides the guideline for designing resonant tank and nonresonant tank as well as selecting proper deadtime for the proposed circuit. With resonant operation feature of the proposed circuit, zero current switching is realized on all switching devices to help the high-efficiency operation of the proposed converter. Through the proposed design methodology in this paper, power loss on switching devices and planar inductors can be minimized. In addition, detailed power loss analysis and breakdown provide hints for further efficiency improvement. Simulation has been performed to validate the operating principle of the proposed STC. A designed 6x STC (450 W nominal/600 W maximum) based on eGaNFETs is demonstrated. With 54 V typical input voltage, the output of the 6x STC is 9 V. The GaN-based prototype achieves a peak efficiency of 98.55%. Also, it achieves 97.18% efficiency and 750 W/in3 power density at 450 W. [ABSTRACT FROM AUTHOR]

Automotive point-of-load dc–dc converters have a wide input voltage range from 4.5 to 42 V and, in order to avoid the AM band interference and comply with the strict CISPR-25 standard for electromagnetic interference (EMI) performance, the switching frequency is desired to be higher than 2 MHz. Buck converter is currently employed for such applications owing to its simplicity and low cost, but it has low efficiency at high switching frequencies and high EMI noise emission due to hard switching. A new active-clamp buck converter is proposed in this paper, which features zero-voltage-switching for main and auxiliary switches, and soft turnoff for synchronous rectifier over a wide input voltage range. The detailed operating principle analysis and several important design considerations are presented. Extensive design equations that can be adapted for other specifications and applications are also derived. A 2.2 MHz, 5V/5A prototype converter with only Silicon mosfets has been designed, built, and tested. The experimental results verify the converter operation and demonstrate the superior performance of the proposed active-clamp buck converter. [ABSTRACT FROM PUBLISHER]