Best Paper Award 2013

Best Paper Award

Fast Computational Method for Human Dosimetry due to Wireless Power Transfer with Magnetic Resonance

Shogo Tsuchida , Ilkka Laakso , Akimasa Hirata

[Trans. Electron.（JPN Edition）, Vol. J96-C No.6, Jun. 2013]

Shogo Tsuchida

Ilkka Laakso

Akimasa Hirata

　Wireless power transfer (WPT) is an emerging technology with a number of potential applications. For WPT systems operating in the MHz band, electric power of up to several kilowatts is transmitted wirelessly between two coils using a strong resonant electromagnetic field. One of the major obstacles to product implementation of WPT technologies is concern about human exposure to the electromagnetic fields utilized in WPT systems. The strengths of these fields could exceed the maximum allowable limits specified in international guidelines and/or standards. Currently, there are no standardized techniques for assessment of human exposure in the frequency band used for WPT. This situation raises the need for detailed evaluation of the specific absorption rate (SAR) in realistic human models, which to date has been costly and time-consuming.
　One of the main contributions of this paper is its proposal of a very effective computational technique for determining the induced electromagnetic field in a realistic human model. The technique consists of efficient implementation of the geometric multi-grid method for solving the quasi-static electromagnetic scalar potential equation in a heterogeneous structure such as a human body. Compared to previously used methods, the technique can achieve performance as much as 300 times faster, which enables accurate computer-based human exposure assessment in any kind of realistic exposure scenario. The proposed technique could be used to characterize human exposure in various scenarios, utilizing multiple individualized numerical anatomical models. A major finding is that worst-case exposure occurs when the coupled coils are located in front of the chest, maximizing the magnetic flux passing through the body.
　In summary, the novel methodology proposed in this study enables human safety evaluation, and the presented results clarify the worst-case exposure scenario for WPT systems, thereby contributing to the eventual realization of WPT technologies and standardization of human exposure assessment.