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Article
Publication date: 6 November 2017

Jiali Zhou, Bo Zhang and Dongyuan Qiu

This paper aims to analyze the frequency characteristics of wireless power transfer (WPT) systems with relay resonators in terms of the power delivered to the load and…

Abstract

Purpose

This paper aims to analyze the frequency characteristics of wireless power transfer (WPT) systems with relay resonators in terms of the power delivered to the load and system efficiency. Based on the analytical results, system parameters can be optimized to achieve maximum power transfer and higher system efficiency.

Design/methodology/approach

Based on Kirchhoff’s voltage law equations, WPT systems with relay resonators are described by the coupled linear second-order differential equations. Splitting frequencies are estimated by using the matrix theory. In addition, critical coupling conditions are demonstrated based on discriminant analysis.

Findings

It was found that multi-maximum values exist for the power delivered to the load and total system efficiency owing to multiple eigenfrequencies of the system. Also, frequency conditions of maximum power transfer and system efficiency, as well as their critical coupling conditions, were quantitatively estimated.

Research limitations/implications

During our analytical process, we assume that quality factors of resonators in the system are high and the crossing coupling between resonators is negligible.

Originality/value

In previous works, the exact analysis of frequency characteristics is limited to WPT systems with two resonators. The appealing feature of this work lies in its ability to present a simplified analytical method with negligible approximation errors for WPT systems with relay resonators.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 20 January 2020

Suqi Liu and Yuping Liu

The impedance compensation approaches have been adopted to achieve the maximum output power and transfer efficiency in many magnetic coupling resonance wireless power

Abstract

Purpose

The impedance compensation approaches have been adopted to achieve the maximum output power and transfer efficiency in many magnetic coupling resonance wireless power transfer projects. However, it remains a challenge to obtain the constant output power and transfer efficiency in a fixed-frequency mode during variations in transfer distance and orientation of the coils. In this paper, using two series transmitting coils to achieve the constant output power and transfer efficiency is used.

Design/methodology/approach

First, the circuit model is established and transfer characteristics are studied. Second, using the two series transmitting coils to achieve the constant output power and transfer efficiency is investigated. Finally, the experimental system is designed; it can optimize the transfer performances by itself; the constant output power and transfer efficiency are achieved in the fixed-frequency mode.

Findings

When the receiving coil moves between the two series transmitting coils, the tolerance of the output power and transfer efficiency is less than 5 per cent.

Research limitations/implications

When a receiving coil is placed between the two series transmitting coils, there are space limits. The receiving coil only shifts between the two transmitting coils.

Practical implications

However, the rail guide vehicle may achieve constant output power and transfer efficiency when it moves on the rail guide. So, this topology may provide a practical solution.

Originality/value

In this research, the three-coil MCR-WPT system including two series transmitting coils is presented. In a fixed-frequency mode, the constant output power and transfer efficiency is achieved in experiments during variations in transfer distance and orientation of the coils. The fluctuation of the output power and transfer efficiency is less than 5 per cent.

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Article
Publication date: 27 November 2019

Suqi Liu and Jianping Tan

This paper aims to find an approach that achieves constant output power and transfer efficiency in an open space, such as charging pads.

Abstract

Purpose

This paper aims to find an approach that achieves constant output power and transfer efficiency in an open space, such as charging pads.

Design/methodology/approach

In this study, a topology of the five-coil system including two transmitting coils is presented. Also, in a fixed-frequency mode and an open space, this study focuses on the two transmitting coils to achieve the uniform magnetic field and ultimately, attain the constant output power and transfer efficiency.

Findings

In a fixed-frequency mode and an open space, the constant output power and transfer efficiency is then achieved in experiments by inserting the relay loop into the uniform magnetic field.

Practical implications

An approach that achieves constant output power and transfer efficiency in an open space. The topology of the five-coil magnetically coupled resonant-wireless power transfer (MCR-WPT) system shows prospective value for various applications, which could be used at designing of wireless battery charger dedicated for cars or mobile phones.

Originality/value

By comparing the simulation and experimental results, the topology can be optimized in the transmission performance by itself. By doing so, the constant output power and transfer ef?ciency are achieved in the constant frequency mode.

Details

Circuit World, vol. 46 no. 1
Type: Research Article
ISSN: 0305-6120

Keywords

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Article
Publication date: 3 July 2017

Yusmarnita Yusop, Mohd. Shakir Md. Saat, Siti Huzaimah Husin, Sing Kiong Nguang and Imran Hindustan

This paper aims to present a new wireless power transfer technique using capacitive coupling. The capacitive power transfer (CPT) system has been introduced as an…

Abstract

Purpose

This paper aims to present a new wireless power transfer technique using capacitive coupling. The capacitive power transfer (CPT) system has been introduced as an attractive alternative to the traditional inductive coupling method. The CPT offers benefits such as simple topology, fewer components, better electromagnetic interference (EMI) performance and robustness to surrounding metallic elements.

Design/methodology/approach

A class-E inverter together with and without inductor capacitor (LC) matching circuit has been utilised in this work because of its ability to perform the DC-to-AC inversion efficiently with significant reduction in switching losses. The validity of the proposed concept has been verified by conducting a laboratory experiment of the CPT system.

Findings

The performances for both systems are analysed and evaluated. A 9.7 W output power is generated through a combined interface [printed circuit board (PCB) plate] capacitance of 2.82 nF at an operating frequency of 1 MHz, with 97 per cent efficiency for 0.25 mm coupling gap distance.

Originality value

An efficient CPT system with class-E LC matching topology is proposed in this paper. With this topology, the zero-voltage switching can be achieved even if the load is different by properly designing the LC matching transformation circuit.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 13 August 2018

Suqi Liu and Jianping Tan

The purpose of this paper is to study the wireless power transfer (WPT) system that always achieves the maximum output power at a fixed angular frequency using the dynamic…

Abstract

Purpose

The purpose of this paper is to study the wireless power transfer (WPT) system that always achieves the maximum output power at a fixed angular frequency using the dynamic impedance compensation and also the maximum transfer efficiency.

Design/methodology/approach

An efficient topology of the WPT system is proposed which states that the functions of the relay are transformed into the functions of the compensator in the three-coil WPT system.

Findings

Increasing the ratio of the frequency detuning factor of the compensator relative to the frequency detuning factor of the compensator also causes the curves of the normalized output power and the transfer efficiency to move toward the high frequency direction.

Practical implications

The scheme of the dynamic compensation for the WPT using a compensator is convenient to obtain the dynamic impedance compensation by adding or removing the capacitances or inductances from the compensator.

Originality/value

The functions of the relay are transformed into the functions of the compensator in the three-coil WPT system.

Details

Circuit World, vol. 44 no. 4
Type: Research Article
ISSN: 0305-6120

Keywords

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Article
Publication date: 6 November 2017

Quandi Wang, Yingcong Wang, Jianwei Kang and Wanlu Li

The purpose of this paper is to present a monitoring method for a three-coil wireless power transfer (WPT) system, which consists of a transmitting coil (Tx), a relay coil…

Abstract

Purpose

The purpose of this paper is to present a monitoring method for a three-coil wireless power transfer (WPT) system, which consists of a transmitting coil (Tx), a relay coil and a movable receiving coil (Rx). Both an ideal resistance and a rectifier bridge load are taken into account.

Design/methodology/approach

From the perspective of fundamental component, the equivalent impedance of a rectifier bridge load is well analyzed. On the basis of the circuit model of a three-coil WPT, estimation equations of the variable mutual inductances and load condition are deduced. Multi-frequency input impedance obtained by frequency scans combined with the Newton-Raphson method are used to obtain solutions.

Findings

Experimental results indicate that the estimated parameter values are close to each other when different sets of source frequencies are applied. When compared with simulation results, these estimated parameters including both mutual inductances and load resistances are found to be accurate.

Originality/value

Using only the information of input side, the proposed algorithm can estimate the mutual inductances and load resistance regardless of the Rx positions. Estimation is feasible for the system with a rectifier bridge load. The estimated analysis will serve as a key step in load power stabilization for WPT systems.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 3 July 2017

Vladimir Kindl, Michal Frivaldsky, Pavol Spanik, Marek Piri and Viliam Jaros

This paper aims to develop mathematical models of variously compensated wireless energy transfer (WET) systems. Attention is primarily paid to the derivation of the most…

Abstract

Purpose

This paper aims to develop mathematical models of variously compensated wireless energy transfer (WET) systems. Attention is primarily paid to the derivation of the most important energy transfer characteristics such as efficiency and amount of transferred power. This paper discusses the main advantages and disadvantages of various compensation techniques to show their possible application areas. On the basis of these results, a designer will be able to quickly identify which compensation type suites as the best solution to fulfill a given system’s requirements.

Design/methodology/approach

First, the current state in the field of mathematical modeling of WET systems is introduced. Next, the non-resonant magnetic-coupled circuit together with four most common resonant magnetic-coupled circuits is analyzed. The equivalent circuit models using loop currents methodology is applied to the analyses. The proposed methodology is experimentally verified by the laboratory measurement of selected circuit topology. The main contribution of the proposed methodology lies in its quick applicability on more complicated or extended systems while keeping a relatively good match with the real system’s behavior.

Findings

The authors have presented the usage of a simple and accurate methodology for investigating variously compensated WET systems. Electrical engineers who require effective and powerful tools for the identification of basic WET systems properties will find this methodology to be of extensive help.

Research limitations/implications

The analyses consider only the sinusoidal type of supply voltage; so, it is valid mainly for the close range of the resonant state. Nonlinearities cannot be taken into account.

Practical implications

This research may be applied in the field of WET systems.

Originality/value

Research in the area of power electronic systems, which provides a clear and straightforward procedure for WET system identification, will be helpful to most practical technicians who are not well versed in areas of physical-based phenomena.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 7 March 2016

Jing Zhou, Yuqing Gao, Xiaoyan Huang and Youtong Fang

Consider the mutual coupling between loads, the purpose of this paper is to study the total transmission efficiency based on different load coil positions relative to the…

Abstract

Purpose

Consider the mutual coupling between loads, the purpose of this paper is to study the total transmission efficiency based on different load coil positions relative to the charging platform, to provide the theoretical basis for the design and parameter optimization of one-to-multiple wireless charging platform.

Design/methodology/approach

Based on the dual-load series-resonant wireless power transfer system, the expression of system efficiency and its calculation model is achieved using the equivalent circuit theory. Finally, a 96 kHz magnetic resonance wireless power transmission test platform is built up to verify the theoretical analysis given in this paper.

Findings

For the completely resonant circuit, the transmission efficiency can be improved by increasing the transmitter-receiver coupling and reducing the coupling between receivers. The total transmission efficiency achieves its lowest value when two loads are with equal competitive capability.

Originality/value

Through the simulation analysis of efficiency formula, the selection principle of impact factors can be applied to the optimization analysis of the transmission efficiency.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 35 no. 2
Type: Research Article
ISSN: 0332-1649

Keywords

Content available
Article
Publication date: 3 May 2021

Habeeba Khan, Sayyed Arif Ali, Mohd Wajid and Muhammad Shah Alam

In this work, a microstrip antenna array for wireless power transfer (WPT) application is reported. The proposed 4 × 4 antenna array operating at 16 GHz is designed using…

Abstract

Purpose

In this work, a microstrip antenna array for wireless power transfer (WPT) application is reported. The proposed 4 × 4 antenna array operating at 16 GHz is designed using a flexible Kapton polyimide substrate for a far-field charging unit (FFCU).

Design/methodology/approach

The proposed antenna is designed using the transmission line model on a flexible Kapton polyimide substrate. The finite element method (FEM) is used to perform the full-wave electromagnetic analysis of the proposed design.

Findings

The antenna offers −10 dB bandwidth of 240 MHz with beam width and broadside gain found to be 29.4° and 16.38 dB, respectively. Also, a very low cross-polarization level of −34.23 dB is achieved with a radiation efficiency of 36.67%. The array is capable of scanning −15° to +15° in both the elevation and azimuth planes.

Originality/value

The radiation characteristics achieved suggest that the flexible substrate antenna is suitable for wireless charging purposes.

Details

Frontiers in Engineering and Built Environment, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 2634-2499

Keywords

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Article
Publication date: 6 July 2012

Sucheng Liu, Luowei Zhou, Weiguo Lu and Anxin Li

The purpose of this paper is to model and analyze energy transfer through near‐field resonant coupling for high power light‐emitting diode (HPLED) illumination, with the…

Abstract

Purpose

The purpose of this paper is to model and analyze energy transfer through near‐field resonant coupling for high power light‐emitting diode (HPLED) illumination, with the intention to increase the appreciation and use of the coupled mode theory (CMT) other than the usual equivalent circuit method.

Design/methodology/approach

The CMT is extensively used to analyze the wireless energy transfer system because of its generality, simplicity, accuracy and intuitive understanding of near‐field resonant energy coupling mechanism.

Findings

The CMT forms a general way to model and analyze the non‐radiative magnetic resonant coupling systems. It is suitable not only for low frequency coupling but also for high frequency (of million‐Hertz) in which the circuit parameters are not easily obtained. Optimal coupling condition corresponding to the maximum power transfer is identified based on the CMT, and the multiple limit cycle phenomenon caused by the nonlinear nature of the HPLED is also described on the CMT model.

Originality/value

This paper takes advantages of CMT, i.e. generality, simplicity, accuracy and intuitive understanding to analyze the near‐field resonant energy coupling system. Key characteristics of the systems are explored based on the CMT, not the usual equivalent circuit method. The influence of nonlinear nature of the high power LED on energy transfer is also investigated. This work seeks a more general way than conventional equivalent circuit method to model and analyze the resonant magnetic system and the results obtained could facilitate better understanding of the resonant magnetic coupling mechanism and optimal design of the near‐field energy transfer system.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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