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Improved Calculation Method of Coupling Factors for Low-Frequency Wireless Power Transfer Systems
Jangyong Ahn1, Seon-Eui Hong2, Haerim Kim1
1The CCS Graduate School of Green Transportation, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34051, Korea.
International Journal of Environmental Research and Public Health
|January 11, 2022
Summary
This study introduces an improved method for calculating coupling factors in electromagnetic field (EMF) safety assessments. By using the 99.99th percentile, it reduces computational errors in human body models, ensuring more accurate EMF exposure evaluations.
Area of Science:
- Electromagnetics
- Computational Physics
- Human Body Modeling
Background:
- International Electrotechnical Commission (IEC) standards 62311 and 62233 define coupling factors for electromagnetic field (EMF) product safety assessments.
- Numerical calculations are required to determine internal human body quantities for coupling factor computation.
- At frequencies below 10 MHz, numerical methods can introduce segmentation or discretization errors, leading to computational artifacts in internal electric field and current density calculations.
Purpose of the Study:
- To propose and validate an improved method for calculating coupling factors that mitigates computational artifacts.
- To ensure accurate localized exposure assessments for electromagnetic field sources near the human body.
- To enhance the reliability of compliance testing for wireless power transfer (WPT) systems.
Main Methods:
- Developed a novel calculation approach applying the 99.99th percentile to determine coupling factors.
- Removed computational artifacts by avoiding the use of maximum values, which may contain abnormal peaks.
- Validated the proposed method using diverse human body models and wireless power transfer (WPT) systems.
Main Results:
- The proposed 99.99th percentile method effectively reduces computational errors in coupling factor calculations.
- Computational errors were decreased by up to 65.3% compared to conventional methods.
- The improved method yields uniform coupling factors, ensuring accurate compliance with reference levels and basic restrictions.
Conclusions:
- The 99.99th percentile approach provides a more robust and accurate method for calculating coupling factors in EMF safety assessments.
- This technique enhances the reliability of product safety evaluations, particularly for low-frequency EMF sources.
- The findings contribute to more precise compliance testing for devices like wireless power transfer systems.
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