A Direct Isolated AC–AC Converter Topology

Chuyue Ji; Jiayang Wu; Jiayu Zhou; Siew-Chong Tan; Shu-Yuen Ron Hui

doi:10.1109/TPEL.2026.3715395

A Direct Isolated AC–AC Converter Topology

Chuyue Ji
, Jiayang Wu^*
, Jiayu Zhou
, Siew-Chong Tan
, Shu-Yuen Ron Hui

^*Corresponding author for this work

Department of Electrical Engineering

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

Abstract

In this paper, a direct isolated AC–AC converter is proposed for efficient single-active-stage power conversion from a line-frequency input AC voltage to a MHz-level output AC voltage. Soft-switching is achieved for both sides' power switches and the diode on the secondary side. Compared to existing solutions, the proposed converter mainly achieves: 1) galvanic isolation between the input and output sides through a simplified single-stage structure; 2) parasitic-assisted passive lossless snubber for the primary-side switch; and 3) efficient, wide-range power regulation within a narrow frequency band. A 1 MHz, 58 W prototype was designed and experimentally tested to validate the converter's performance, demonstrating 90.05% AC–AC efficiency at the rated offline condition of 110 V / 60 Hz AC input. © 2026 IEEE.

Original language	English
Pages (from-to)	20916-20932
Number of pages	17
Journal	IEEE Transactions on Power Electronics
Volume	41
Issue number	12
Online published	20 Jul 2026
DOIs	https://doi.org/10.1109/TPEL.2026.3715395
Publication status	Online published - 20 Jul 2026

Funding

This work was supported by the Hong Kong Research Grant Council through the GRF Project under Grant 11201326.

Research Keywords

Direct AC–AC converter
galvanic isolation
passive lossless snubber
single active power stage
zero-current switching (ZCS)
zero-voltage switching (ZVS)

RGC Funding Information

RGC-funded

Access Output

10.1109/TPEL.2026.3715395

Other Access Options

Check CityUHK Library

Permanent Link

Right click to copy link

Cite this

@article{ad6f971db7124dada73c760bb7dc45e6,

title = "A Direct Isolated AC–AC Converter Topology",

abstract = "In this paper, a direct isolated AC–AC converter is proposed for efficient single-active-stage power conversion from a line-frequency input AC voltage to a MHz-level output AC voltage. Soft-switching is achieved for both sides' power switches and the diode on the secondary side. Compared to existing solutions, the proposed converter mainly achieves: 1) galvanic isolation between the input and output sides through a simplified single-stage structure; 2) parasitic-assisted passive lossless snubber for the primary-side switch; and 3) efficient, wide-range power regulation within a narrow frequency band. A 1 MHz, 58 W prototype was designed and experimentally tested to validate the converter's performance, demonstrating 90.05\% AC–AC efficiency at the rated offline condition of 110 V / 60 Hz AC input. {\textcopyright} 2026 IEEE.",

keywords = "Direct AC–AC converter, galvanic isolation, passive lossless snubber, single active power stage, zero-current switching (ZCS), zero-voltage switching (ZVS)",

author = "Chuyue Ji and Jiayang Wu and Jiayu Zhou and Siew-Chong Tan and Hui, \{Shu-Yuen Ron\}",

year = "2026",

month = jul,

day = "20",

doi = "10.1109/TPEL.2026.3715395",

language = "English",

volume = "41",

pages = "20916--20932",

journal = "IEEE Transactions on Power Electronics",

issn = "0885-8993",

publisher = "IEEE",

number = "12",

}

TY - JOUR

T1 - A Direct Isolated AC–AC Converter Topology

AU - Ji, Chuyue

AU - Wu, Jiayang

AU - Zhou, Jiayu

AU - Tan, Siew-Chong

AU - Hui, Shu-Yuen Ron

PY - 2026/7/20

Y1 - 2026/7/20

N2 - In this paper, a direct isolated AC–AC converter is proposed for efficient single-active-stage power conversion from a line-frequency input AC voltage to a MHz-level output AC voltage. Soft-switching is achieved for both sides' power switches and the diode on the secondary side. Compared to existing solutions, the proposed converter mainly achieves: 1) galvanic isolation between the input and output sides through a simplified single-stage structure; 2) parasitic-assisted passive lossless snubber for the primary-side switch; and 3) efficient, wide-range power regulation within a narrow frequency band. A 1 MHz, 58 W prototype was designed and experimentally tested to validate the converter's performance, demonstrating 90.05% AC–AC efficiency at the rated offline condition of 110 V / 60 Hz AC input. © 2026 IEEE.

AB - In this paper, a direct isolated AC–AC converter is proposed for efficient single-active-stage power conversion from a line-frequency input AC voltage to a MHz-level output AC voltage. Soft-switching is achieved for both sides' power switches and the diode on the secondary side. Compared to existing solutions, the proposed converter mainly achieves: 1) galvanic isolation between the input and output sides through a simplified single-stage structure; 2) parasitic-assisted passive lossless snubber for the primary-side switch; and 3) efficient, wide-range power regulation within a narrow frequency band. A 1 MHz, 58 W prototype was designed and experimentally tested to validate the converter's performance, demonstrating 90.05% AC–AC efficiency at the rated offline condition of 110 V / 60 Hz AC input. © 2026 IEEE.

KW - Direct AC–AC converter

KW - galvanic isolation

KW - passive lossless snubber

KW - single active power stage

KW - zero-current switching (ZCS)

KW - zero-voltage switching (ZVS)

UR - https://www.scopus.com/pages/publications/105045788828

UR - https://www.scopus.com/pages/publications/105045788828#tab=impact

U2 - 10.1109/TPEL.2026.3715395

DO - 10.1109/TPEL.2026.3715395

M3 - RGC 21 - Publication in refereed journal

SN - 0885-8993

VL - 41

SP - 20916

EP - 20932

JO - IEEE Transactions on Power Electronics

JF - IEEE Transactions on Power Electronics

IS - 12

ER -

A Direct Isolated AC–AC Converter Topology

Abstract

Funding

Research Keywords

RGC Funding Information

Access Output

Other Access Options

Permanent Link

Other Files and Links

Fingerprint

TBRS: High-Frequency, High-Power and High-Efficiency Wireless Power Transfer Technologies

Cite this

A Direct Isolated AC–AC Converter Topology

Abstract

Funding

Research Keywords

RGC Funding Information

Access Output

Other Access Options

Permanent Link

Other Files and Links

Fingerprint

Projects

TBRS: High-Frequency, High-Power and High-Efficiency Wireless Power Transfer Technologies

Cite this