Experimental Verification of Impedance Matching Method for Repeater to Improve Spatial Freedom of 6.78 MHz Resonant Inductive Coupling Wireless Power Transfer Systems

Fujiki, Keita; Ishihara, Masataka; Umetani, Kazuhiro; Hiraki, Eiji

doi:10.23919/epe.2019.8915171

Cited by 7 publications

(9 citation statements)

References 19 publications

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“…Equation (20) present that Rx coil is influenced by other Tx coils and Rx coils. By changing Equations ( 19) and ( 20) into matrix form, we can obtain Equations ( 21) and (22).…”

Section: Optimal Mimo Impedance Matching Solutionmentioning

confidence: 99%

“…Substituting Equation (22) into Equation ( 21) and simplifying it, we get Rx current vector in Equation (24) and the current vector went through the voltage source in Equation (25).…”

Section: Optimal Mimo Impedance Matching Solutionmentioning

confidence: 99%

“…Lu et al have used printed spiral coils with impedance matching networks for wireless energy transfer [21]. Fujiki et al have applied impedance matching networks to wireless energy transmission systems with repeaters for the purpose of reducing frequency splitting [22]. Boo et al have proposed an analysis and impedance matching optimization of a wireless energy transfer system with a rotating coil [23]; however, it can only be used on SISO CMR systems.…”

Section: Introductionmentioning

confidence: 99%

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Adaptive Impedance Matching Scheme for Magnetic MIMO Wireless Power Transfer System

Zhao

Liu

2021

Electronics

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In coupled magnetic resonance (CMR) wireless energy transfer systems, the energy transfer power is low and the power transfer efficiency changes with the coil position. One reason for this reduction in power and efficiency is the impedance mismatching (IM) between the Tx and Rx coils; achieving impedance matching for multiple-input multiple-output (MIMO) CMR IM wireless power transmission (WPT) is quite complex due to the uncertainty in the number of coils and the interaction between coils. In this paper, we provide an analytical model of MIMO CMR which fully formulates the complex relationship between multiple Tx and Rx channels. Then, we design an impedance matching network (IMN) for MIMO CMR and derive an optimal IM solution. Base on this solution, we also develop an adaptive impedance matching scheme to control IMN, based on an automatic analysis of MIMO CMR system; the resulting control scheme achieves optimal values for transmission power and efficiency through IMN and coil selection. The simulation results indicate that the scheme is able to automatically adjust the impedance matching network according to the changes of the relative positions between Tx and Rx coils to achieve high energy transfer power and efficiency.

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“…Equation (20) present that Rx coil is influenced by other Tx coils and Rx coils. By changing Equations ( 19) and ( 20) into matrix form, we can obtain Equations ( 21) and (22).…”

Section: Optimal Mimo Impedance Matching Solutionmentioning

confidence: 99%

“…Substituting Equation (22) into Equation ( 21) and simplifying it, we get Rx current vector in Equation (24) and the current vector went through the voltage source in Equation (25).…”

Section: Optimal Mimo Impedance Matching Solutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Adaptive Impedance Matching Scheme for Magnetic MIMO Wireless Power Transfer System

Zhao

Liu

2021

Electronics

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“…However, the high-quality factor of the repeater resonator can further cause another problem, i.e. the frequency splitting phenomenon (8)- (11) , in which this optimal frequency deviates from the operating frequency of the transmitter inverter depending on the intensity of the magnetic coupling. These problems lead to extreme difficulty in matching the resonant frequency of the repeater resonator with this optimal frequency by manual adjustment of the resonant capacitor.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, many WPT systems need to be operated within a narrow frequency bandwidth due to the restriction of the industrial use of the high-frequency electromagnetic field. Particularly, the Industrial Scientific Medical (ISM) band (11) (15) (16) is convenient for comparatively low-power WPT systems. However, this narrow bandwidth of the ISM band is difficult to accept adjustment of the operating frequency.…”

Section: Introductionmentioning

confidence: 99%

Autonomous Resonant Frequency Tuner for a 6.78MHz Inductive Coupling Wireless Power Transfer System to Stably Maximize Repeater Current

et al. 2023

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Recently, the resonant inductive coupling wireless power transfer (RIC-WPT) technique is being widely used to charge small IoT devices dispersed in a wide area, e.g., an office desk and warehouse rack. In this application, the repeater is utilized to expand the chargeable area without an additional AC power source. The repeater comprises a LC resonator commonly with a high-quality factor to induce large current in the repeater coil. However, this causes the problem that the repeater performance is highly susceptible to the variation in its resonant frequency due to the manufacturing tolerance of coil inductance and resonant capacitance as well as the variation of the magnetic coupling between the transmitter and repeater coils. To solve this problem, a previous study has proposed a concept of the autonomous resonant frequency tuning circuit to stably maximize repeater coil current, although this study implemented a part of this control system as a practical circuit. This paper aims to develop a complete autonomous resonant frequency tuning circuit that implements the aforementioned concept. The proposed circuit adjusts the resonant frequencies of the transmitter and repeater by utilizing the Automatic Tuning Assist Circuits. These frequencies are optimized using the infrared wireless signal communication from the transmitter to the repeater. Along with the operating principle of the proposed circuit, this study presents detailed circuit design as well as the experimental results, which verified the stable autonomous maximization of the repeater coil current against the variation in the resonant frequency of the repeater resonator.

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Feasibility of Active Reactance Compensator for Autonomously Maximizing Repeater Coil Current of Wireless Power Transfer System Against Variations in Resonant Frequency and Magnetic Coupling Intensity

Ishihara,

Umetani,

Konishi

et al. 2024

IEEE Access

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Experimental Verification of Impedance Matching Method for Repeater to Improve Spatial Freedom of 6.78 MHz Resonant Inductive Coupling Wireless Power Transfer Systems

Cited by 7 publications

References 19 publications

Adaptive Impedance Matching Scheme for Magnetic MIMO Wireless Power Transfer System

Adaptive Impedance Matching Scheme for Magnetic MIMO Wireless Power Transfer System

Autonomous Resonant Frequency Tuner for a 6.78MHz Inductive Coupling Wireless Power Transfer System to Stably Maximize Repeater Current

Feasibility of Active Reactance Compensator for Autonomously Maximizing Repeater Coil Current of Wireless Power Transfer System Against Variations in Resonant Frequency and Magnetic Coupling Intensity

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