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Energies
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Wireless Power Transfer and RF Technologies
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Wireless Power Transfer and RF Technologies

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

Deadline for manuscript submissions: closed (1 October 2021) | Viewed by 12668

Special Issue Editor

Dr. Dong-Wook Seo

E-Mail Website
Guest Editor
Interdisciplinary Major of Maritime AI Convergence, Korea Maritime and Ocean University, Busan 49112, Republic of Korea
Interests: wireless power transfer; biomedical implantable device; energy harvesting system; radar cross section (RCS); automotive radar system; mmWave antenna; applied RF/microwave
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

I would like to invite original and review articles to a Special Issue of the Journal Energies on the topic of “Wireless Power Transfer and RF Technologies.”

Wireless power transfer (WPT) technologies have been developed to wirelessly supply power to various devices such as mobile devices, electric vehicle, home appliance, and bikes. Despite several decades of progress in WPT technologies, the inductive WPT system still provides a short transmission distance as large as the size of transmitting/receiving coils. This is why various links and structures, from multiple links of the multiple-input multiple-output (MIMO) structure to RF links, have been attempted to expand the transmission distance. In particular, RF technologies have been highly anticipated as potentially able to realize breakthrough transmission distance.

The topics of this Special Issue include, but are not limited to, recent advances and emerging technologies for WPT, various applications of WPT systems, RF energy harvesting, and coil/antenna structures for WPT.

Dr. Dong-Wook Seo
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 2600 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

  • Inductive wireless power transfer
  • RF/mmWave based wireless power transfer
  • RF energy harvesting
  • Near-Field Focused Antenna for wireless power transfer
  • Algorithms or schemes to improve the power transfer efficiency
  • Optimum displacement of coils/antennas for multiple receivers
  • Applications of wireless power transfer system.

Published Papers (6 papers)

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Editorial

Jump to: Research

3 pages, 168 KiB  
Editorial
Wireless Power Transfer and RF Technologies
by Dong-Wook Seo
Energies 2021, 14(24), 8301; https://doi.org/10.3390/en14248301 - 9 Dec 2021
Cited by 1 | Viewed by 1667
Abstract
This book contains the successful submissions [...] Full article
(This article belongs to the Special Issue Wireless Power Transfer and RF Technologies)

Research

Jump to: Editorial

17 pages, 6388 KiB  
Article
Automatic Resonance Compensation for Efficient WPT via Magnetic Resonance Coupling Using Flexible Coils
by Sousuke Nakamura, Katsuki Baba and Takahiro Miyaura
Energies 2021, 14(17), 5254; https://doi.org/10.3390/en14175254 - 25 Aug 2021
Cited by 5 | Viewed by 1630
Abstract
With the recent proliferation of mobile and wearable devices, wireless power transfer (WPT) has gained attention as an up-and-coming technology to charge these devices. In particular, WPT via magnetic resonance coupling has attracted considerable interest for day-to-day applications since it is harmless to [...] Read more.
With the recent proliferation of mobile and wearable devices, wireless power transfer (WPT) has gained attention as an up-and-coming technology to charge these devices. In particular, WPT via magnetic resonance coupling has attracted considerable interest for day-to-day applications since it is harmless to the human body and has relatively long transmission distance. However, it was difficult to be installed into environment (e.g., utensils and furniture) and flexible objects in the living space since the use of flexible coils leads to the decrease in transmission efficiency due to the collapse of the resonance caused by coil deformation. Therefore, this study proposes an automatic resonance compensation system that automatically compensates the inductance variation caused by coil deformation using a circuit that can electronically control the equivalent capacitance (a capacity control circuit), and thereby maintains the resonant state. An experiment was conducted to verify whether the efficiency was maintained when the coil deformed. The results indicated a transmission efficiency nearly as high as that of the ideal resonant state as well as a highly responsive control, and therefore, the proposed system has a good potential for use in real-world applications. Full article
(This article belongs to the Special Issue Wireless Power Transfer and RF Technologies)
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23 pages, 13412 KiB  
Article
Analysis on Influences of Intra-Couplings in a MISO Magnetic Beamforming Wireless Power Transfer System
by Kyungtae Kim, Han-Joon Kim, Dong-Wook Seo and Ji-Woong Choi
Energies 2021, 14(16), 5184; https://doi.org/10.3390/en14165184 - 22 Aug 2021
Cited by 5 | Viewed by 2191
Abstract
Magnetic beamforming techniques can enhance the power transfer efficiency using focused magnetic fields by the multiple transmitters to the receivers. However, the intra-couplings that cause power leakage and phase distortion among the arrayed coils inevitably occur due to the deployment of coils having [...] Read more.
Magnetic beamforming techniques can enhance the power transfer efficiency using focused magnetic fields by the multiple transmitters to the receivers. However, the intra-couplings that cause power leakage and phase distortion among the arrayed coils inevitably occur due to the deployment of coils having strong couplings between each other. Here, we analyze the adverse influences of intra-couplings and present the advantages of magnetically independent transmitters for multiple-inputs and single-output (MISO) WPT. The independent coil array can achieve focused magnetic fields by simply adjusting the amplitude of the transmitter voltage source without phase adjustment. The system also can eliminate the reactive power with the independent coil array to efficiently use the supplying power from the source. The analytical studies are verified by numerical and circuit simulation and experiments. Our analysis can be generalized to the MISO-WPT with an arbitrary number of transmitters. It can provide insight into designing and implementing the MISO-WPT applying magnetic beamforming. Full article
(This article belongs to the Special Issue Wireless Power Transfer and RF Technologies)
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15 pages, 3005 KiB  
Article
Impedance Matching Method for 6.78 MHz Class-E2-Based WPT System
by Yi Zhang, Yue Feng, Sheng Liu, Jiande Wu and Xiangning He
Energies 2021, 14(14), 4289; https://doi.org/10.3390/en14144289 - 15 Jul 2021
Cited by 3 | Viewed by 1855
Abstract
The performance of a conventional Class-E2-based WPT system is sensitive to system parameters such as the coil coupling coefficient and load variation. System efficiency decreases rapidly when the coil coupling coefficient and load deviate from their optimum values. In this paper, an impedance [...] Read more.
The performance of a conventional Class-E2-based WPT system is sensitive to system parameters such as the coil coupling coefficient and load variation. System efficiency decreases rapidly when the coil coupling coefficient and load deviate from their optimum values. In this paper, an impedance matching method and a design procedure are proposed to maintain high system efficiency over a wider range of coupling coefficient and load variations. The load-pull technique is adopted to identify the high-efficiency load region of a Class-E power amplifier (PA), and a double-L-type impedance matching network (IMN) is proposed to transform the load impedance of a Class-E PA into a high-efficiency working region. Compared to a single L-type IMN, a double-L-type IMN is more flexible and has better tuning performance. A 6.78 MHz Class-E2-based WPT system was built to validate the proposed design method. The experimental results show that the proposed double-L-type IMN can significantly attenuate the decline in Class-E PA efficiency when system parameters dynamically change. With a double-L-type IMN, the WPT system could maintain high efficiency (over 55%) under a wider range of coil coupling coefficient and load variations. The peak system efficiency reached 83.2% with 13.7 W output power. The impedance matching method and design procedure in this paper could provide a practical solution for building a high-efficiency WPT system with strong robustness. Full article
(This article belongs to the Special Issue Wireless Power Transfer and RF Technologies)
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16 pages, 5240 KiB  
Article
Power-Generation Optimization Based on Piezoelectric Ceramic Deformation for Energy Harvesting Application with Renewable Energy
by Hyeonsu Han and Junghyuk Ko
Energies 2021, 14(8), 2171; https://doi.org/10.3390/en14082171 - 13 Apr 2021
Cited by 9 | Viewed by 3229
Abstract
Along with the increase in renewable energy, research on energy harvesting combined with piezoelectric energy is being conducted. However, it is difficult to predict the power generation of combined harvesting because there is no data on the power generation by a single piezoelectric [...] Read more.
Along with the increase in renewable energy, research on energy harvesting combined with piezoelectric energy is being conducted. However, it is difficult to predict the power generation of combined harvesting because there is no data on the power generation by a single piezoelectric material. Before predicting the corresponding power generation and efficiency, it is necessary to quantify the power generation by a single piezoelectric material alone. In this study, the generated power is measured based on three parameters (size of the piezoelectric ceramic, depth of compression, and speed of compression) that contribute to the deformation of a single PZT (Lead zirconate titanate)-based piezoelectric element. The generated power was analyzed by comparing with the corresponding parameters. The analysis results are as follows: (i) considering the difference between the size of the piezoelectric ceramic and the generated power, 20 mm was the most efficient piezoelectric ceramic size, (ii) considering the case of piezoelectric ceramics sized 14 mm, the generated power continued to increase with the increase in the compression depth of the piezoelectric ceramic, and (iii) For piezoelectric ceramics of all diameters, the longer the depth of deformation, the shorter the frequency, and depending on the depth of deformation, there is a specific frequency at which the charging power is maximum. Based on the findings of this study, PZT-based elements can be applied to cases that receive indirect force, including vibration energy and wave energy. In addition, the power generation of a PZT-based element can be predicted, and efficient conditions can be set for maximum power generation. Full article
(This article belongs to the Special Issue Wireless Power Transfer and RF Technologies)
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20 pages, 8748 KiB  
Article
Predictive Controller Design for a Three-Winding Inductive Power Transfer System
by Tian-Hua Liu, Muhammad Syahril Mubarok and Zheng-Jun Liu
Energies 2021, 14(6), 1549; https://doi.org/10.3390/en14061549 - 11 Mar 2021
Cited by 1 | Viewed by 1154
Abstract
Inductive power transfer (IPT) systems have become more and more popular recently. To improve transient responses and load disturbance responses, this paper proposes a predictive controller design for a three-winding inductive power transfer (IPT) system. First, a three-winding IPT is presented. Next, a [...] Read more.
Inductive power transfer (IPT) systems have become more and more popular recently. To improve transient responses and load disturbance responses, this paper proposes a predictive controller design for a three-winding inductive power transfer (IPT) system. First, a three-winding IPT is presented. Next, a predictive controller is designed based on augmented variables and a performance index. Finally, a digital signal processor, TMS 320F2808, made by Texas Instrument, is used to execute the predictive control algorithms and to control the switching states of the power devices. An IPT system, with DC 220 V input, DC 130 V output, and a rated power of 2 kW, is implemented. A buck converter is used to provide an adjustable output voltage and output current to charge a battery set. Experimental results show that the proposed predictive controllers of the IPT system have better performance than proportional-integral (PI) controllers, including faster transient responses and better load disturbance responses. Full article
(This article belongs to the Special Issue Wireless Power Transfer and RF Technologies)
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