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Special Issue "Research on Wireless Power Transfer System"

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A: Electrical Engineering".

Deadline for manuscript submissions: 20 October 2022 | Viewed by 8324

Special Issue Editor

Prof. Dr. ByoungHee Lee
E-Mail Website
Guest Editor
Department of Electronics and Control Engineering, Hanbat National University, Daejeon, Korea
Interests: DC/DC converter; wireless power transfer; AC/DC converter; Hybrid Power Conversion System

Special Issue Information

Dear Colleagues,

Wireless power transfer (WPT) Technology has been researched over the years for improving the quality of the life in terms of, for example, convenience and safety when supplying power to load systems or charging the energy system is required. Due to the increase of applications, the need for more applicable methods and techniques arises in order to properly design the WPT system and enhance the merits of WPT technology.

The Special Issue invites original research papers to address new technology of WPT systems in order to improve the performance of the WPT system and extend the application of WPT technology. Additionally, authors are encouraged to submit papers addressing the state-of-the-art and recent advancements in the areas, providing useful guidelines for future research directions.

Prof. Dr. ByoungHee Lee
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2200 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Improvement of power transfer efficiency
  • Misalignment improvement
  • System analysis
  • Optimal power control
  • Standby power reduction
  • Effects on the human body.

Published Papers (10 papers)

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Research

Article
Proposal of Wireless Charging Which Enables Magnetic Field Suppression at Foreign Object Location
Energies 2022, 15(3), 1028; https://doi.org/10.3390/en15031028 - 29 Jan 2022
Cited by 1 | Viewed by 786
Abstract
In the wireless power transmission (WPT) to electric vehicles (EVs) in parking lots, there is a risk of abnormal heat generation due to the absorption of the magnetic field in metallic foreign objects. Accordingly, currently available products are equipped with a function that [...] Read more.
In the wireless power transmission (WPT) to electric vehicles (EVs) in parking lots, there is a risk of abnormal heat generation due to the absorption of the magnetic field in metallic foreign objects. Accordingly, currently available products are equipped with a function that automatically halts power transmission when a metallic foreign object is detected. However, if possible, continuing power transmission while suppressing the magnetic field absorption may be an another solution. Therefore, this paper proposes a novel function which enables wireless power transmission with high efficiency while suppressing the magnetic field absorption of metallic foreign objects. In this study, it was assumed that a metallic foreign body was present in an arbitrary point in a two-dimensional plane and the power transmission was conducted by the phased array WPT. An algorithm using particle swarm optimization (PSO) to search for the optimal combination of the phase and amplitude of the coil input voltages together with coil arrangements, in terms of both magnetic field suppression and transmission efficiency, is proposed. The simulation was performed with the lower efficiency boundary set as 85% and the load power set as 11 kW, in reference to the SAE J2954 standard. As a result, it was confirmed that the magnetic field suppression effect increased in accordance with the increase in the number of transmission (Tx) coils, thus indicating the effectiveness of the proposed algorithm. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
Efficiency of the Wireless Power Transfer System with Planar Coils in the Periodic and Aperiodic Systems
Energies 2022, 15(1), 115; https://doi.org/10.3390/en15010115 - 24 Dec 2021
Cited by 2 | Viewed by 943
Abstract
This article presents the results of the proposed numerical and analytical analysis of the Wireless Power Transfer System (WPT). The system consists of a transmitting surface and a receiving surface, where each of them is composed of planar spiral coils. Two WPT systems [...] Read more.
This article presents the results of the proposed numerical and analytical analysis of the Wireless Power Transfer System (WPT). The system consists of a transmitting surface and a receiving surface, where each of them is composed of planar spiral coils. Two WPT systems were analysed (periodic and aperiodic) considering two types of coils (circular and square). In the aperiodic system, the adjacent coils were wound in the opposite direction. The influence of the type of coils, the winding direction, the number of turns, and the distance between the coils on the efficiency of the WPT system was compared. In periodic models, higher efficiency was obtained with circular rather than square coils. The results obtained with both proposed methods were consistent, which confirmed the correctness of the adopted assumptions. In aperiodic models, for a smaller radius of the coil, the efficiency of the system was higher in the square coil models than in the circular coil models. On the other hand, with a larger radius of the coil, the efficiency of the system was comparable regardless of the coil type. When comparing both systems (periodic and aperiodic), for both circular and square coils, aperiodic models show higher efficiency values (the difference is even 57%). The proposed system can be used for simultaneous charging of many sensors (located in, e.g., walls, floors). Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
Parameter Optimization of Double LCC MCRWPT System Based on ZVS
Energies 2021, 14(17), 5309; https://doi.org/10.3390/en14175309 - 26 Aug 2021
Cited by 1 | Viewed by 437
Abstract
At present, magnetically coupled resonance wireless power transfer (MCRWPT) is the main technology used in electric vehicle wireless power transfer (WPT) due to its advantages of high transmission power and high efficiency. The resonant compensation circuit of the system generally adopts the double [...] Read more.
At present, magnetically coupled resonance wireless power transfer (MCRWPT) is the main technology used in electric vehicle wireless power transfer (WPT) due to its advantages of high transmission power and high efficiency. The resonant compensation circuit of the system generally adopts the double LCC (DLCC) structure, which has many capacitor and inductor components. Therefore, it is necessary to optimize the circuit parameters to improve the transmission performance of the system. In this study, the DLCC compensation circuit was modeled and analyzed to lay the foundation for parameter optimization. Secondly, the size parameters of the energy transmitting and receiving coil were determined, and the influence of the change of the primary and secondary compensation inductance on the circuit element stress and output performance was analyzed to determine the optimal compensation inductance value. Thirdly, the realization condition of zero voltage switching (ZVS) was analyzed, the relationship between the input impedance angle of the compensation circuit and the component parameter value was obtained, and a parameter optimization control strategy for realizing ZVS was proposed. Finally, through simulation and experiment, it was concluded that under different power levels, the efficiency of the parameter optimization strategy proposed in this study is as high as 91.86%, increasing by about 1%. Therefore, the research undertaken in this study can promote the development of WPT technology and has certain practical significance. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
Comparison of the Efficiency and Load Power in Periodic Wireless Power Transfer Systems with Circular and Square Planar Coils
Energies 2021, 14(16), 4975; https://doi.org/10.3390/en14164975 - 13 Aug 2021
Cited by 3 | Viewed by 643
Abstract
In the article, a wireless charging system with the use of periodically arranged planar coils is presented. The efficiency of two wireless power transfer (WPT) systems with different types of inductors, i.e., circular and square planar coils is compared, and two models are [...] Read more.
In the article, a wireless charging system with the use of periodically arranged planar coils is presented. The efficiency of two wireless power transfer (WPT) systems with different types of inductors, i.e., circular and square planar coils is compared, and two models are proposed: analytical and numerical. With the appropriate selection of a load resistance, it is possible to obtain either the maximum efficiency or the maximum power of a receiver. Therefore, the system is analyzed at two optimum modes of operation: with the maximum possible efficiency and with the highest power transmitted to the load. The analysis of many variants of the proposed wireless power transfer solution was performed. The aim was to check the influence of the geometry of the coils and their type (circular or square) on the efficiency of the system. Changes in the number of turns, the distance between the coils (transmit and receive) as well as frequency are also taken into account. The results obtained from analytical and numerical analysis were consistent; thus, the correctness of the adopted circuit and numerical model (with periodic boundary conditions) was confirmed. The proposed circuit model and the presented numerical approach allow for a quick estimate of the electrical parameters of the wireless power transmission system. The proposed system can be used to charge many receivers, e.g., electrical cars on a parking or several electronic devices. Based on the results, it was found that the square coils provide lower load power and efficiency than compared to circular coils in the entire frequency range and regardless of the analyzed geometry variants. The results and discussion of the multivariate analysis allow for a better understanding of the influence of the coil geometry on the charging effectiveness. They can also be valuable knowledge when designing this type of system. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
Shielded Capacitive Power Transfer (S-CPT) without Secondary Side Inductors
Energies 2021, 14(15), 4590; https://doi.org/10.3390/en14154590 - 29 Jul 2021
Cited by 1 | Viewed by 477
Abstract
In this study, we propose a four-plate structure with two shielding plates to produce shielded capacitive power transfer (S-CPT) at an operating frequency of 6.78 MHz for a 10 W system. By eliminating the inductors at the secondary side to form an asymmetrical [...] Read more.
In this study, we propose a four-plate structure with two shielding plates to produce shielded capacitive power transfer (S-CPT) at an operating frequency of 6.78 MHz for a 10 W system. By eliminating the inductors at the secondary side to form an asymmetrical topology, an S-CPT system was developed with a class-E power amplifier. Using MATLAB software, analysis was performed to obtain the parameters in the S-CPT system regarding resonance and impedance matching, and the proposed coupler structure was investigated through electric field simulation. The shield plate voltage stability was also investigated by analysing both the simulation and hardware experiment results. A prototype of S-CPT was established to validate the analysis results and to demonstrate the voltage at the shield plate of the proposed coupler structure. The experimental results are in good agreement with the simulation results. The proposed S-CPT exhibits an AC–AC efficiency of 84%, with a 56% voltage ground stability reduction because of implementing a balun. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
LCC-S-Based Integral Terminal Sliding Mode Controller for a Hybrid Energy Storage System Using a Wireless Power System
Energies 2021, 14(6), 1693; https://doi.org/10.3390/en14061693 - 18 Mar 2021
Cited by 7 | Viewed by 741
Abstract
Unlike the plug-in charging system, which has safety concerns such as electric sparks, wireless power transfer (WPT) is less-time consuming, is environmentally friendly and can be used in a wet environment. The inclusion of hybrid energy storage systems (HESSs) in electric vehicles (EVs) [...] Read more.
Unlike the plug-in charging system, which has safety concerns such as electric sparks, wireless power transfer (WPT) is less-time consuming, is environmentally friendly and can be used in a wet environment. The inclusion of hybrid energy storage systems (HESSs) in electric vehicles (EVs) has helped to increase their energy density as well as power density. Combined with static wireless power transfer, a WPT–HESS system is proposed in this article. The HESS system includes a battery and supercapacitor (SC) connected to a WPT system through DC–DC converters. To ensure a stable DC bus voltage, an inductor–capacitor–capacitor series (LCC-S) compensation network has been implemented in the WPT system. Utilizing the two-port network theory, the design equations of the LCC-S compensation network are derived in order to realize the maximum efficiency point for the WPT system. To ensure that the WPT system operates at this maximum efficiency point and that the SC is charged to its maximum capacity, an energy management system (EMS) has been devised that generates reference currents for both the SC and battery. An integral terminal sliding mode controller (ITSMC) has been designed to track these reference currents and control the power flow between the energy storage units (ESUs) and WPT system. The stability of the proposed system is validated by Lyapunov theory. The proposed WPT–HESS system is simulated using the MATLAB/Simulink. The robustness of the ITSMC against the widely used proportional–integral–derivative (PID) and sliding mode controller (SMC) is verified under abrupt changes in the associated ESU resistance and reference load current. Finally, the simulations of the WPT–HESS system are validated by controller hardware-in-loop (C-HIL) experiments. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
Dynamic Process Analysis and Voltage Stabilization Control of Multi-Load Wireless Power Supply System
Energies 2021, 14(5), 1466; https://doi.org/10.3390/en14051466 - 08 Mar 2021
Cited by 2 | Viewed by 573
Abstract
At present, wireless power supply technology has gradually attracted people’s attention due to its safety, convenience, and portability. It has become one of the development trends of power supply for future technologies such as electric vehicles. In many engineering applications, inductive wireless power [...] Read more.
At present, wireless power supply technology has gradually attracted people’s attention due to its safety, convenience, and portability. It has become one of the development trends of power supply for future technologies such as electric vehicles. In many engineering applications, inductive wireless power supply systems need to supply power to multiple loads at the same time. Therefore, it is necessary to analyze the dynamic process of the multiload system. This paper first selects the optimal compensation network according to the stable operating conditions of the multiload system. Secondly, in order to classify and describe the movement state of the load in the dynamic process, the simulation model is established on the MATLAB/SIMULINK platform to analyze the influence of the mutual inductance or resistance of any load on the output characteristics of the primary system and other loads. Then, in order to solve the problem of unstable output voltage used by multiple loads entering the same track at the same time or load resistance changes, this paper adopts a secondary side control strategy. The duty cycle of the Buck circuit is adjusted by the fixed frequency PWM sliding mode controller (PWMSMC), so as to realize the independent control of each load. Finally, an experimental platform was established to verify the correctness of the theoretical analysis. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
Maximizing Transfer Efficiency with an Adaptive Wireless Power Transfer System for Variable Load Applications
Energies 2021, 14(5), 1417; https://doi.org/10.3390/en14051417 - 04 Mar 2021
Cited by 1 | Viewed by 820
Abstract
Electronic devices usually operate in a variable loading condition and the power transfer efficiency of the accompanying wireless power transfer (WPT) method should be optimizable to a variable load. In this paper, a reconfigurable WPT technique is introduced to maximize power transfer efficiency [...] Read more.
Electronic devices usually operate in a variable loading condition and the power transfer efficiency of the accompanying wireless power transfer (WPT) method should be optimizable to a variable load. In this paper, a reconfigurable WPT technique is introduced to maximize power transfer efficiency in a weakly coupled, variable load wireless power transfer application. A series-series two-coil wireless power network with resonators at a frequency of 150 kHz is presented and, under a variable loading condition, a shunt capacitor element is added to compensate for a maximum efficiency state. The series capacitance element of the secondary resonator is tuned to form a resonance at 150 kHz for maximum power transfer. All the capacitive elements for the secondary resonators are equipped with reconfigurability. Regardless of the load resistance, this proposed approach is able to achieve maximum efficiency with constant power delivery and the power present at the load is only dependent on the input voltage at a fixed operating frequency. A comprehensive circuit model, calculation and experiment is presented to show that optimized power transfer efficiency can be met. A 50 W WPT demonstration is established to verify the effectiveness of this proposed approach. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
Inductive Power Transfer Subsystem for Integrated Motor Drive
Energies 2021, 14(5), 1412; https://doi.org/10.3390/en14051412 - 04 Mar 2021
Cited by 2 | Viewed by 616
Abstract
An inductive power transfer subsystem for an integrated motor drive is presented in this paper. First, the concept of an integrated motor drive system is overviewed, and its main components are described. Next, the paper is focused on its inductive power transfer subsystem, [...] Read more.
An inductive power transfer subsystem for an integrated motor drive is presented in this paper. First, the concept of an integrated motor drive system is overviewed, and its main components are described. Next, the paper is focused on its inductive power transfer subsystem, which includes a magnetically coupled resonant circuit and two-stage energy conversion with an appropriate control method. Simplified complex domain analysis of the magnetically coupled resonant circuit is provided and the applied procedure for its component selection is explained. Furthermore, the prototype of the integrated motor drive system with its control is described. Finally, the prototype based on the gallium nitride field effect transistors (GaN FET) inductive power transfer subsystem is experimentally tested, confirming the feasibility of the concept. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Article
Estimation of the Maximum Efficiency and the Load Power in the Periodic WPT Systems Using Numerical and Circuit Models
Energies 2021, 14(4), 1151; https://doi.org/10.3390/en14041151 - 22 Feb 2021
Cited by 7 | Viewed by 813
Abstract
The article presents an analysis of the maximum efficiency and maximum load power, which are available to obtain in periodic wireless power transfer (WPT) systems. The numerical computations of the proposed WPT structures are performed using the finite element method and branch current [...] Read more.
The article presents an analysis of the maximum efficiency and maximum load power, which are available to obtain in periodic wireless power transfer (WPT) systems. The numerical computations of the proposed WPT structures are performed using the finite element method and branch current method. Two theoretical models are discussed, i.e., a numerical model with simplified structure and boundary conditions as well as an equivalent circuit model is proposed to solve WPT systems with many magnetically coupled planar coils. A multivariate analysis is performed, which takes into account the variability of the number of turns, distance between a transmitting and receiving coil, and the frequency of an energy source. The outputs, such as overall efficiency, power of the source and power transferred to a load are discussed. The formulas for the load impedance required to maximize the efficiency or load power, which are taking into account the electrical parameters of the system resulting from its geometry, are presented. The results obtained from proposed models are consistent, which confirm the correctness of the adopted circuit model, which is less complex and faster to compute than numerical one. It is also possible to perform a quick assessment of electrical parameters of the analyzed WPT structure, using presented analytical formulas and numerical model or experimental data. The results allow for a detailed discussion of the dependence of the efficiency and power of the WPT system with respect to geometry of spiral coils. Full article
(This article belongs to the Special Issue Research on Wireless Power Transfer System)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Comparative Analysis of Wireless Power Transmission System with Two Transmitting Coils for Correction of Misalignment of Transceiver Coils
Authors: KyeongWon Bang and KangHyun Yi
Affiliation: Electronics Engineering, Daegu University, Republic of Korea
Abstract: Misalignment of the transmitting coil and the receiving coil is a major cause of lowering the efficiency of the wireless power transfer (WPT) system. Misalignment is not necessarily perfect because it is affected by the user's skill in using the device. In this paper, we propose a method to analyze and correct the output voltage of WPT according to the coupling coefficient change due to lateral misalignment in a multi-transmitter WPT system with SS topology. In general, the misalignment lowers the coupling coefficient between the transceivers and causes a decrease in output power and efficiency. At this time, if the impedance of the transmitter due to the change of the coupling coefficient is adjusted to be the same as before the misalignment occurs, it is possible to achieve significant transmission efficiency correction by minimizing reactive power even in the misalignment state. This control method, which requires multiple transmitters for the control method, is suitable for a transmitter having a multi-coil structure and can be applied to a double-D(DD) type coil commonly used for charging electric vehicles (EVs). The proposed control method was analyzed and verified through HFSS simulation, MAXWELL simulation, and PSIM simulation.

Title: Comparison of the efficiency of the wireless charging system for planar coils in a periodic and checkerboard type pattern
Authors: Jacek Maciej Stankiewicz, Agnieszka Choroszucho
Affiliation: Department of Electrical Engineering, Power Electronics and Power Engineering, Faculty of Electrical Engineering, Bialystok University of Technology, Wiejska 45D, 15-351 Bialystok, Poland
Abstract: The article presents results for numerical and analytical analysis of Wireless Power Transfer system (WPT) consisting of transmitting and receiving planar spiral coils. Two types of coils (circular and square) were included in the analysis. Two coil systems were also considered: periodic and checkerboard. The difference between the proposed systems lies in the different method of winding the coils. In the periodic system, all coils are wound in the same direction. But in the checkerboard-type system turns are wound in the opposite direction. The influence of the type of the coils, the winding direction, the number of turns and the distance between the coils on the efficiency of the WPT system was compared. The analysis covered a wide range of frequency from 100 kHz to 1000 kHz. The Finite Element Method (FEM) with the use of periodic or antiperiodic boundary conditions was used for the analysis. In the periodic model, greater efficiency was obtained with circular rather than square coils (e.g. 5% -20% for 1 MHz). In the checkerboard-type configuration, for a smaller radius of the coil, system efficiency was greater in square coil models than in circular coil models. On the other hand, with larger radius of the coil, the efficiency of the system was comparable regardless of the type of the coil. Proposed WPT system could be used to charge electric devices as the wireless power transfer system. The results indicate at which system parameters wireless energy transfer is possible.

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