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| Efficiency Enhancement Methods for Magnetically Coupled Wireless Power Transfer Systems Based on Dispersive Medium Parameter Optimization |
| Liao Zhijuan, Yi Jialin, Tian Hao, Lu Guanyu, Xia Chenyang |
| School of Electrical Engineering China University of Mining and Technology Xuzhou 221116 China |
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Abstract Metamaterial-based magnetic-coupling wireless power transfer (MC-WPT) has received widespread attention and has become a research hotspot in electrical engineering. Current research primarily focuses on application-level implementations and the optimized combination of existing structures. However, the internal electromagnetic characteristics of metamaterials—particularly the key parameters that influence dielectric loss and corresponding mechanisms—are not yet fully understood. Revealing these fundamental properties and clarifying the key parameters affecting dielectric loss are crucial for enhancing system performance and guiding the design of novel metamaterials.
This paper conducts an in-depth analysis of the internal electromagnetic properties of metamaterials from a “mechanistic perspective”. First, the general mathematical models are established for the constitutive parameters of dispersive media, time-averaged electromagnetic energy storage, dissipation, magnetic interaction strength, and damping coefficient. Subsequently, using a normalization method, the frequency and damping characteristics of the dispersive media are analyzed. The mechanism of the real and imaginary parts of the constitutive parameters on electromagnetic energy storage and dissipation is clarified. Then, frequency and damping tuning methods are presented. Furthermore, a novel metamaterial design approach is proposed that comprehensively considers near-field coupling effects. It avoids resonance frequency drift and reduces the internal resistance of spiral conductors. This method overcomes the limitations of conventional designs, which often focus only on the real part of permeability and rely on unit-cell behavior to represent overall performance.
An experimental platformwas constructedfor a metamaterial-based MC-WPT system. The metamaterial structure, with collaborative frequency- or damping-optimization that considers coupling effects, significantly enhanced system performance. Under aligned coil conditions, applying frequency or damping control alone improved system efficiency by approximately 2%. In contrast, the synergistic optimization of both frequency and damping yielded an efficiency increase of 4.1%~5.2% and a power boost of 5%~7%. For misaligned coils, at three offset positions - (10 mm, 0 mm, 15 cm), (0 mm, 18 mm, 15 cm), and (10 mm, 18 mm, 15 cm) - the introduction of the NMM medium plate increased transfer efficiency by 5.42%, 3.67% and 8.6%, respectively, with power rising by 0.11 W, 0.34 W, and 0.68 W, respectively. By employing the optimized NMM slab, transfer efficiency was further enhanced by 5.53%, 3.35%, and 9.86%, and output power increased by 0.40 W, 0.39 W, and 0.71 W, respectively. The optimized metamaterial was verified for enhancing the system's misalignment tolerance.
The main contributions and conclusions are as follows. (1) The general mathematical models are established for the constitutive parameters of dispersive media, time-averaged electromagnetic energy storage, dissipation, magnetic interaction strength, and damping coefficient. (2) The mechanisms by which the real and imaginary parts of the constitutive parameters influence electromagnetic energy storage and dissipation are elucidated. Under the constraints of the dispersive medium’s constitutive relations, the real part of permeability affects energy storage characteristics, while the imaginary part directly reflects magnetic loss intensity. (3) Methods for tuning frequency and damping are provided, and a metamaterial design strategy is proposed. The performance of real and imaginary parts is optimized.
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Received: 16 April 2025
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2026, Vol. 41 
