Analysis of Magnetically Coupled Wireless Power Transmission for Maximum Efficiency

Kim, Chung-Ju; Lee, Bomson

doi:10.5515/jkiees.2011.11.3.156

Cited by 13 publications

(21 citation statements)

References 6 publications

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“…A method of extracting the coupling coefficients (or mutual inductance) was suggested in [10]. These expressions have been found to agree well with the results extracted with [10].…”

Section: Introductionsupporting

confidence: 69%

“…The calculation of the mutual inductance between inclined circular coils is also provided in [6,9]. A method of extracting the coupling coefficients (or mutual inductance) was suggested in [10]. These expressions have been found to agree well with the results extracted with [10].…”

Section: Introductionsupporting

confidence: 69%

“…When each loop is resonant at a resonant angular frequency (ω 0 ), the current on each loop can be easily obtained. Details can be found in [10]. One compact but meaningful expression for the power transfer efficiency was obtained as…”

Section: Calculation Of Mutual Inductance Andmentioning

confidence: 99%

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Alternative Expressions for Mutual Inductance and Coupling Coefficient Applied in Wireless Power Transfer

Kim¹,

Lee²

2016

Journal of electromagnetic engineering and science

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Alternative analytic expressions for the mutual inductance (Lm) and coupling coefficient (k) between circular loops are presented using more familiar and convenient expressions that represent the property of reciprocity clearly. In particular, the coupling coefficients are expressed in terms of structural dimensions normalized to a geometric mean of radii of two loops. Based on the presented expressions, various aspects of the mutual inductances and coupling coefficients, including the regions of positive, zero, and negative value, are examined with respect to their impacts on the efficiency of wireless power transmission. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ⓒ

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“…A method of extracting the coupling coefficients (or mutual inductance) was suggested in [10]. These expressions have been found to agree well with the results extracted with [10].…”

Section: Introductionsupporting

confidence: 69%

Section: Introductionsupporting

confidence: 69%

See 1 more Smart Citation

Alternative Expressions for Mutual Inductance and Coupling Coefficient Applied in Wireless Power Transfer

Kim¹,

Lee²

2016

Journal of electromagnetic engineering and science

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“…A conventional WPT system consists of two main resonators for the transmitter and receiver, which operate at the same resonance frequency [1][2][3]. This system, however, has a limitation on the distance between transmitter and receiver for achieving high WPT efficiency.…”

Section: ⅰ Introductionmentioning

confidence: 99%

New Analysis Method for Wireless Power Transfer System with Multiple n Resonators

Kim¹,

Park²,

Lee³

2013

Journal of electromagnetic engineering and science

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This paper presents a new method for analyzing the maximum efficiency of a wireless power transfer (WPT) system with multiple n resonators. The method is based on ABCD matrices and allows transformation of the WPT system with multiple n resonators into a single two-port network system. The general maximum efficiency equation of a WPT system with multiple n resonators is derived using the ABCD matrix. Use of this equation allows placement of the relay resonators for maximum efficiency even though they are asymmetrical. The general maximum efficiency equation and the method of the optimum placement are verified by a full wave simulation. The results show that the method is useful for the analysis of a WPT system with relay resonators. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Ⅰ. IntroductionMany researchers are currently investigating magnetically coupled wireless power transfer (WPT) systems. A conventional WPT system consists of two main resonators for the transmitter and receiver, which operate at the same resonance frequency [1][2][3]. This system, however, has a limitation on the distance between transmitter and receiver for achieving high WPT efficiency. This limitation can be overcome by using some resonators as relays between the two main resonators [4]. The WPT system is then composed of multiple n resonators, which can achieve a higher WPT efficiency than a conventional WPT system can at the same distance. This system is well analyzed in [5] with respect to the general circuit model and the maximum efficiency with a matched load. However, the general maximum efficiency equation of a WPT system with multiple n resonators described in [5] becomes complicated when analyzing the type of system normally utilized for practical applications.This paper proposes a new analysis method for the WPT system with multiple n resonators. The method simplifies the entire WPT system into a single two port network expressed by an ABCD matrix. The general maximum efficiency equation of the WPT system with multiple n resonators can then be obtained with elements of the ABCD matrix. This equation provides a much more convenient way to obtain the maximum efficiency and the optimum placement of the asymmetrical relays for the best utilization. The general maximum efficiency equation and the method of the optimum placement of the asymmetrical relays are verified by a full wave simulation of ANSYS HFSS (high frequency structural simulator). Ⅱ. New Analysis Method Using the ABCD MatrixThe schematic diagram of a WPT system with multiple n resonators is shown in Fig. 1(a). The non-adjacent coupling coefficient is ignored since it is very small in a practical WPT system with the relays. Thus, the WPT system with multiple n resonators can be considered as n-1 parts of ...

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“…A number of approaches followed in many aspects in an effort to realize similar left-handed characteristics [2][3][4][5]. However, most of these showed high losses and narrow operating bandwidth (having a very sharp slope near the resonant frequency).…”

Section: ⅰ Introductionmentioning

confidence: 99%

Simplified Modeling of Ring Resonators and Split Ring Resonators Using Magnetization

Jeon¹,

Lee²

2013

Journal of electromagnetic engineering and science

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This paper examines various aspects of the electromagnetic responses of the ring resonator located in the transverse electromagnetic cell. In addition, an equivalent circuit for the ring resonator is proposed and analyzed based on the electromagnetic phenomenon of the resonator. The equivalent circuit was simply modeled based on the concept of magnetization. A method for achieving a wider operating bandwidth of the negative permeability is provided. The ring resonator with its resonant frequency of 13.56 MHz was designed and its characteristics were examined in terms of S-parameters, effective permeability, loss rate, bandwidth, etc. The circuit and electromagnetic simulation results show an excellent agreement as well as that of theory. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Ⅰ. IntroductionThe realization of media having negative permittivity and permeability, so called left-handed metamaterial, became feasible after 1991 when Pendry et al.[1] proposed a new method that used an array of thin wires and split ring resonators (SRRs). A number of approaches followed in many aspects in an effort to realize similar left-handed characteristics [2][3][4][5]. However, most of these showed high losses and narrow operating bandwidth (having a very sharp slope near the resonant frequency). In fact, the problem of SRRs has seldom been approached seriously from an engineering viewpoint, although many trials have been made. Basically, SRRs are similar to the ring resonator in their characteristics. In this paper, we model the ring resonator (SRRs) starting from the definition of a magnetic dipole moment and leading to a useful equivalent circuit. The mechanism of SRRs is explained with more familiar terms than in [1]. In addition, we provide a method of realizing the negative permeability over a large bandwidth. It is believed that the presented modeling will provide significant convenience and flexibility for the realization of the left-handed materials. Ⅱ. Novel Modeling of a Ring Resonator (SRRs)We have modeled the ring resonator using an equivalent circuit. The dimensions of the ring resonator and its orientation with respect to the given transverse electromagnetic (TEM) wave are depicted in Fig. 1. The wave travels in the z-direction with the electric and magnetic fields oriented in the x-and y-directions, respectively. The radius of the loop is r and the radius of the ring is rring. The side length of the unit cell is a. C is the value of the chip capacitor. It is inserted for resonance of the ring resonator which has some inductance L originally. The total resistance R of the ring resonator is given bywhere Rr is the radiation resistance, Rl is the ohmic resistance, and RL is an additionally loaded resistance which is 0 originally, but can be added ...

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Analysis of Magnetically Coupled Wireless Power Transmission for Maximum Efficiency

Cited by 13 publications

References 6 publications

Alternative Expressions for Mutual Inductance and Coupling Coefficient Applied in Wireless Power Transfer

Alternative Expressions for Mutual Inductance and Coupling Coefficient Applied in Wireless Power Transfer

New Analysis Method for Wireless Power Transfer System with Multiple n Resonators

Simplified Modeling of Ring Resonators and Split Ring Resonators Using Magnetization

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