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Understanding near-field wireless power transfer systems with complex mutual inductance and negative mutual resistance
File(s)
Author(s)
Hui, Shu Yuen Ron
Li, Kerui
Yu, Jinfeng
Tan, Siew Chong
Type
Journal Article
Abstract
Mutual inductance traditionally appears as a scalar quantity in electric circuit theory. However, in wireless power transfer (WPT) systems with dissipative media such as seawater and human tissues, the complex nature of mutual inductance has been observed. Another phenomenon of negative mutual resistance (NMR) also puzzles many engineers in the WPT community. While complex mutual inductance (CMI) and NMR have been studied separately in the literature, they cannot be separated in many WPT systems. This article reviews and examines CMI and NMR in a holistic manner for WPT. Based on electric circuit theory, this article presents an extended WPT theory with a generalized analysis and circuit model of WPT systems to explain the physical nature and coexistence of CMI and NMR. This extended WPT theory shows that these two elements not only co-exist in WPT systems with dissipative media but also in any WPT system with at least one extra induced dissipative current loop in intended relay resonators and unintended conducting paths such as unintended metallic objects and electromagnetic shielding materials. A methodology for optimizing the WPT systems using the CMI and NMR through recompensation of the resonator design to enhance mutual coupling is provided. The theory is illustrated with several WPT examples with practical measurements and simulations.
Date Issued
2026-08-01
Date Acceptance
2026-04-13
Citation
IEEE Journal of Emerging and Selected Topics in Power Electronics, 2026, 14 (4), pp.4419-4439
URI
URL
DOI
ISSN
2168-6777
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Start Page
4419
End Page
4439
Journal / Book Title
IEEE Journal of Emerging and Selected Topics in Power Electronics
Volume
14
Issue
4
Copyright Statement
© 2026 The Authors. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/
License URL
Publication Status
Published
Date Publish Online
2026-05-07