An consideration on equivalent circuit of wireless power transmission

Hirayama, Hiroshi; Okuyama, Yuki; Kikuma, Nobuyoshi; Sakakibara, Kunio

doi:10.1109/antem.2010.5552569

Cited by 10 publications

(6 citation statements)

References 2 publications

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“…The difference between the two systems is the existence of one-loop coils (primary coils) for feeding and receiving power. Note that the existence of the primary coil is shown to be insignificant for transfer efficiency (Amano et al 2011). Thus, both cases are considered here.…”

Section: Modelling Resonant Coilsmentioning

confidence: 99%

Confirmation of quasi-static approximation in SAR evaluation for a wireless power transfer system

Hirata¹,

Ito²,

Laakso³

2013

Phys. Med. Biol.

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The present study discusses the applicability of the magneto-quasi-static approximation to the calculation of the specific absorption rate (SAR) in a cylindrical model for a wireless power transfer system. Resonant coils with different parameters were considered in the 10 MHz band. A two-step quasi-static method that is comprised of the method of moments and the scalar-potential finite-difference methods is applied, which can consider the effects of electric and magnetic fields on the induced SAR separately. From our computational results, the SARs obtained from our quasi-static method are found to be in good agreement with full-wave analysis for different positions of the cylindrical model relative to the wireless power transfer system, confirming the applicability of the quasi-static approximation in the 10 MHz band. The SAR induced by the external electric field is found to be marginal as compared to that induced by the magnetic field. Thus, the dosimetry for the external magnetic field, which may be marginally perturbed by the presence of biological tissue, is confirmed to be essential for SAR compliance in the 10 MHz band or lower. This confirmation also suggests that the current in the coil rather than the transferred power is essential for SAR compliance.

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Section: Modelling Resonant Coilsmentioning

confidence: 99%

Confirmation of quasi-static approximation in SAR evaluation for a wireless power transfer system

Hirata¹,

Ito²,

Laakso³

2013

Phys. Med. Biol.

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“…5. Equations (6) and (7) for primary voltage and secondary voltage are written as Eqs. (8) and (9), and therefore currents I 1 and I 2 are calculated as in Eqs.…”

Section: Equivalent Circuit Of N-n Circuitmentioning

confidence: 99%

“…Based on the coupled-mode theory, high-efficiency and large-capacity wireless power transfer via a large gap becomes possible when resonant coils on primary and secondary sides are operated at the same resonance frequency [1,2]. Many reports have been published so far, including explanations based on tuning-fork model [3], proposals of equivalent circuits [4,[6][7][8], interpretation in terms of the bandpass theory [9,10] and k-Q product [11,12], proposal of maximizing efficiency [13], extension of working frequency [14], repeater coils [15,16], power supply to multiple loads [17][18][19][20][21][22], and so on. Application of this technology is expected in various fields.…”

Section: Introductionmentioning

confidence: 99%

Unified Theory of Electromagnetic Induction and Magnetic Resonant Coupling

Imura

Hori

2017

Electrical Engineering Japan

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SUMMARY The difference between electromagnetic induction and magnetic resonant coupling was pointed out in the first proposal of electromagnetic resonant coupling. However, there was no clear technical comparison between the two methods. Therefore, in this study, five circuits are compared by using a phasor diagram, which is a basic and well‐known method in electric circuit theory. The transition from typical electromagnetic induction to magnetic resonant coupling is shown. The mechanism of the high efficiency and high‐power transfer across a large air gap and displacement is discussed, where the primary‐ and secondary‐side resonant frequencies are the same. From the above discussion, we conclude that when the specific conditions of electromagnetic induction are satisfied, the wireless power transfer can be categorized as electromagnetic resonant coupling. The unified theory of electromagnetic induction and magnetic resonant coupling is verified through experiment.

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“…This technology makes possible efficient power transfer allowing for a long transmission distance and positional displacement [5]. Many studies in the field were published so far, including explanations based on a tuning-fork model [3], equivalent circuits [4,[6][7][8], interpretations in terms of bandpass filter theory [9,10] and kQ product [11,12], efficiency improvement [13], expansion of operating frequency band [14], repeater coils [15,16], power transfer to multiple loads [17][18][19][20][21][22], and so on. This technology promises a wide range of applications, being explored for wireless power supply to electric vehicles [23,24], including moving vehicles [25], or to home appliances [26].…”

Section: Introductionmentioning

confidence: 99%

Relation Between Power Transfer and Magnetic Flux in Magnetic Coupling Circuit Using Resonance

Imura

2017

Electrical Engineering Japan

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SUMMARY Magnetic resonant coupling is one of the conditions for electromagnetic induction using a circuit topology. On the other hand, the relation between the main magnetic flux and the near magnetic field has not been sufficiently discussed in the discussion of the circuit topology, even though the main magnetic flux is used for energy transfer in wireless power transfer. The full explanation of the contribution of the main magnetic flux was not proposed with regard to a comparison between the magnetic resonant coupling and the other topologies. Therefore, in this paper, a series of explanations from the main magnetic flux to circuit topologies is presented, and the mechanism of magnetic resonant coupling is proposed with regard to circuit theory and electromagnetism. The proposed theory is validated through an electromagnetic field analysis and experiment.

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An consideration on equivalent circuit of wireless power transmission

Cited by 10 publications

References 2 publications

Confirmation of quasi-static approximation in SAR evaluation for a wireless power transfer system

Confirmation of quasi-static approximation in SAR evaluation for a wireless power transfer system

Unified Theory of Electromagnetic Induction and Magnetic Resonant Coupling

Relation Between Power Transfer and Magnetic Flux in Magnetic Coupling Circuit Using Resonance

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