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5548 KiB

Open AccessArticle

Combined Conformal Strongly-Coupled Magnetic Resonance for Efficient Wireless Power Transfer

by Matjaz Rozman, Michael Fernando, Bamidele Adebisi, Khaled M. Rabie, Rupak Kharel, Augustine Ikpehai and Haris Gacanin

Energies 2017, 10(4), 498; https://doi.org/10.3390/en10040498 - 07 Apr 2017

Cited by 19 | Viewed by 8228

Abstract

This paper proposes a hybrid circuit between a conformal strongly-coupled magnetic resonance (CSCMR) and a strongly-coupled magnetic resonance (SCMR), for better wireless power transmission (WPT). This combination promises to enhance the flexibility of the proposed four-loop WPT system. The maximum efficiency at various [...] Read more.

This paper proposes a hybrid circuit between a conformal strongly-coupled magnetic resonance (CSCMR) and a strongly-coupled magnetic resonance (SCMR), for better wireless power transmission (WPT). This combination promises to enhance the flexibility of the proposed four-loop WPT system. The maximum efficiency at various distances is achieved by combining coupling-matching between the source and transmitting coils along with the coupling factor between the transmitting and receiving coils. Furthermore, the distance between transmitting and receiving coils is investigated along with the distance relationship between the source loop and transmission coil, in order to achieve the maximum efficiency of the proposed hybrid WPT system. The results indicate that the proposed approach can be effectively employed at distances comparatively smaller than the maximum distance without frequency matching. The achievable efficiency can be as high as 84% for the whole working range of the transmitter. In addition, the proposed hybrid system allows more spatial freedom compared to existing chargers. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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5512 KiB

Open AccessArticle

A Novel WPT System Based on Dual Transmitters and Dual Receivers for High Power Applications: Analysis, Design and Implementation

by Yong Li, Ruikun Mai, Tianren Lin, Hongjian Sun and Zhengyou He

Energies 2017, 10(2), 174; https://doi.org/10.3390/en10020174 - 04 Feb 2017

Cited by 48 | Viewed by 6179

Abstract

Traditional Wireless Power Transfer (WPT) systems only have one energy transmission path, which can hardly meet the power demand for high power applications, e.g., railway applications (electric trains and trams, etc.) due to the capacity constraints of power electronic devices. A novel WPT [...] Read more.

Traditional Wireless Power Transfer (WPT) systems only have one energy transmission path, which can hardly meet the power demand for high power applications, e.g., railway applications (electric trains and trams, etc.) due to the capacity constraints of power electronic devices. A novel WPT system based on dual transmitters and dual receivers is proposed in this paper to upgrade the power capacity of the WPT system. The reliability and availability of the proposed WPT system can be dramatically improved due to the four energy transmission paths. A three-dimensional finite element analysis (FEA) tool ANSYS MAXWELL (ANSYS, Canonsburg, PA, USA) is adopted to investigate the proposed magnetic coupling structure. Besides, the effects of the crossing coupling mutual inductances among the transmitters and receivers are analyzed. It shows that the same-side cross couplings will decrease the efficiency and transmitted power. Decoupling transformers are employed to mitigate the effects of the same-side cross couplings. Meanwhile, the output voltage in the secondary side can be regulated at its designed value with a fast response performance, and the system can continue work even with a faulty inverter. Finally, a scale-down experimental setup is provided to verify the proposed approach. The experimental results indicate that the proposed method could improve the transmitted power capacity, overall efficiency and reliability, simultaneously. The proposed WPT structure is a potential alternative for high power applications. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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5233 KiB

Open AccessArticle

A High Efficiency Charging Strategy for a Supercapacitor Using a Wireless Power Transfer System Based on Inductor/Capacitor/Capacitor (LCC) Compensation Topology

by Yuyu Geng, Bin Li, Zhongping Yang, Fei Lin and Hu Sun

Energies 2017, 10(1), 135; https://doi.org/10.3390/en10010135 - 21 Jan 2017

Cited by 46 | Viewed by 8363

Abstract

In the application of rail transit vehicles, when using typical wireless power transfer (WPT) systems with series–series (SS) compensation supply power for supercapacitors, the output current is in an approximately inverse relationship with the duty cycle in a wide range. This renders the [...] Read more.

In the application of rail transit vehicles, when using typical wireless power transfer (WPT) systems with series–series (SS) compensation supply power for supercapacitors, the output current is in an approximately inverse relationship with the duty cycle in a wide range. This renders the typical buck circuit control inappropriate. In order to help resolve the above issues, this paper designs inductor/capacitor/capacitor (LCC) compensation with new compensation parameters, which can achieve an adjustable quasi-constant voltage from the input of the inverter to the output of the rectifier. In addition, the two-port network method is used to analyze the resonant compensation circuit. The analysis shows that LCC compensation is more suitable for the WPT system using the supercapacitor as the energy storage device. In the case of LCC compensation topology combined with the charging characteristics of the supercapacitor, an efficient charging strategy is designed, namely first constant current charging, followed by constant power charging. Based on the analysis of LCC compensation, the system has an optimal load, by which the system works at the maximum efficiency point. Combined with the characteristics of the constant voltage output, the system can maintain high efficiency in the constant power stage by making constant output power the same as the optimal power point. Finally, the above design is verified through experiments. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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12397 KiB

Open AccessEditor’s ChoiceArticle

Wireless DC Motor Drives with Selectability and Controllability

by Chaoqiang Jiang, K.T. Chau, Chunhua Liu and Wei Han

Energies 2017, 10(1), 49; https://doi.org/10.3390/en10010049 - 04 Jan 2017

Cited by 28 | Viewed by 6184

Abstract

This paper proposes and implements the concept of wireless DC motor drives, which can achieve the abilities of selective driving and controllable speed. Due to different resonant frequencies of the multiple energy receivers of the associated DC motor drives, the transmitter can be [...] Read more.

This paper proposes and implements the concept of wireless DC motor drives, which can achieve the abilities of selective driving and controllable speed. Due to different resonant frequencies of the multiple energy receivers of the associated DC motor drives, the transmitter can be purposely tuned to the specified resonant frequency which matches with the specified receiver, hence driving the specified motor selectively. In the meantime, the burst fire control is used to regulate the operating speed of the motor working at the resonant frequency, hence retaining the maximum power transmission efficiency. Both finite element analysis and experimentation are given to verify the validity of the proposed wireless DC motor drive system. For exemplification, three different resonant frequencies, namely 60 kHz, 100 kHz and 140 kHz, are selected to energize three DC motors. Under the burst fire control method, the speed of each motor can be regulated separately and the wireless power transfer (WPT) system can achieve the measured power transmission efficiency of about 60%. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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4149 KiB

Open AccessArticle

Conjugate Image Theory Applied on Capacitive Wireless Power Transfer

by Ben Minnaert and Nobby Stevens

Energies 2017, 10(1), 46; https://doi.org/10.3390/en10010046 - 03 Jan 2017

Cited by 28 | Viewed by 5405

Abstract

Wireless power transfer using a magnetic field through inductive coupling is steadily entering the market in a broad range of applications. However, for certain applications, capacitive wireless power transfer using electric coupling might be preferable. In order to obtain a maximum power transfer [...] Read more.

Wireless power transfer using a magnetic field through inductive coupling is steadily entering the market in a broad range of applications. However, for certain applications, capacitive wireless power transfer using electric coupling might be preferable. In order to obtain a maximum power transfer efficiency, an optimal compensation network must be designed at the input and output ports of the capacitive wireless link. In this work, the conjugate image theory is applied to determine this optimal network as a function of the characteristics of the capacitive wireless link, as well for the series as for the parallel topology. The results are compared with the inductive power transfer system. Introduction of a new concept, the coupling function, enables the description of the compensation network of both an inductive and a capacitive system in two elegant equations, valid for the series and the parallel topology. This approach allows better understanding of the fundamentals of the wireless power transfer link, necessary for the design of an efficient system. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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6945 KiB

Open AccessArticle

Development of a 60 kHz, 180 kW, Over 85% Efficiency Inductive Power Transfer System for a Tram

by Seung-Hwan Lee, Jae-Hee Kim and Jun-Ho Lee

Energies 2016, 9(12), 1075; https://doi.org/10.3390/en9121075 - 16 Dec 2016

Cited by 28 | Viewed by 5539

Abstract

Conventional contact-based train power transfer systems have high maintenance costs and safety issues and cause noise and additional aerodynamic drag. Instead of the conventional system, a loosely coupled online wireless power transfer (WPT) system for a train is proposed in this paper. The [...] Read more.

Conventional contact-based train power transfer systems have high maintenance costs and safety issues and cause noise and additional aerodynamic drag. Instead of the conventional system, a loosely coupled online wireless power transfer (WPT) system for a train is proposed in this paper. The operating frequency of the proposed design is 60 kHz to ensure a low flux density and a high-efficiency system with a large air gap. In addition, a new transmitter track and pick-up geometry for 60 kHz operation are designed using finite element analysis (FEA). The proposed design is evaluated theoretically and experimentally. By using the simulated results, a new 180 kW, 15 m test-bed for a tram is constructed. The total power transfer efficiency is greater than 85% at the rated output power, and the loss distribution in the system is identified. Electromagnetic field (EMF) radiation and the voltage induction at the rail are measured for safety evaluation. The measured EMF satisfied international guidelines. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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5644 KiB

Open AccessArticle

Cost-Effectiveness Comparison of Coupler Designs of Wireless Power Transfer for Electric Vehicle Dynamic Charging

by Weitong Chen, Chunhua Liu, Christopher H.T. Lee and Zhiqiang Shan

Energies 2016, 9(11), 906; https://doi.org/10.3390/en9110906 - 02 Nov 2016

Cited by 66 | Viewed by 8076

Abstract

This paper presents a cost-effectiveness comparison of coupler designs for wireless power transfer (WPT), meant for electric vehicle (EV) dynamic charging. The design comparison of three common types of couplers is first based on the raw material cost, output power, transfer efficiency, tolerance [...] Read more.

This paper presents a cost-effectiveness comparison of coupler designs for wireless power transfer (WPT), meant for electric vehicle (EV) dynamic charging. The design comparison of three common types of couplers is first based on the raw material cost, output power, transfer efficiency, tolerance of horizontal offset, and flux density. Then, the optimal cost-effectiveness combination is selected for EV dynamic charging. The corresponding performances of the proposed charging system are compared and analyzed by both simulation and experimentation. The results verify the validity of the proposed dynamic charging system for EVs. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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838 KiB

Open AccessArticle

Multislot Simultaneous Spectrum Sensing and Energy Harvesting in Cognitive Radio

by Xin Liu, Zhenyu Na, Min Jia, Xuemai Gu and Xiaotong Li

Energies 2016, 9(7), 568; https://doi.org/10.3390/en9070568 - 21 Jul 2016

Cited by 7 | Viewed by 4753

Abstract

In cognitive radio (CR), the spectrum sensing of the primary user (PU) may consume some electrical power from the battery capacity of the secondary user (SU), resulting in a decrease in the transmission power of the SU. In this paper, a multislot simultaneous [...] Read more.

In cognitive radio (CR), the spectrum sensing of the primary user (PU) may consume some electrical power from the battery capacity of the secondary user (SU), resulting in a decrease in the transmission power of the SU. In this paper, a multislot simultaneous spectrum sensing and energy harvesting model is proposed, which uses the harvested radio frequency (RF) energy of the PU signal to supply the spectrum sensing. In the proposed model, the sensing duration is divided into multiple sensing slots consisting of one local-sensing subslot and one energy-harvesting subslot. If the PU is detected to be present in the local-sensing subslot, the SU will harvest RF energy of the PU signal in the energy-harvesting slot, otherwise, the SU will continue spectrum sensing. The global decision on the presence of the PU is obtained through combining local sensing results from all the sensing slots by adopting “Or-logic Rule”. A joint optimization problem of sensing time and time splitter factor is proposed to maximize the throughput of the SU under the constraints of probabilities of false alarm and detection and energy harvesting. The simulation results have shown that the proposed model can clearly improve the maximal throughput of the SU compared to the traditional sensing-throughput tradeoff model. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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4355 KiB

Open AccessArticle

Frequency-Splitting-Free Synchronous Tuning of Close-Coupling Self-Oscillating Wireless Power Transfer

by Po Hu, Jieshuai Ren and Wenan Li

Energies 2016, 9(7), 491; https://doi.org/10.3390/en9070491 - 27 Jun 2016

Cited by 8 | Viewed by 5159

Abstract

The synchronous tuning of the self-oscillating wireless power transfer (WPT) in a close-coupling condition is studied in this paper. The Hamel locus is applied to predict the self-oscillating points in the WPT system. In order to make the system operate stably at the [...] Read more.

The synchronous tuning of the self-oscillating wireless power transfer (WPT) in a close-coupling condition is studied in this paper. The Hamel locus is applied to predict the self-oscillating points in the WPT system. In order to make the system operate stably at the most efficient point, which is the middle resonant point when there are middle resonant and split frequency points caused by frequency-splitting, the receiver (RX) rather than the transmitter (TX) current is chosen as the self-oscillating feedback variable. The automatic delay compensation is put forward to eliminate the influence of the intrinsic delay on frequency tuning for changeable parameters. In addition, the automatic circuit parameter tuning based on the phase difference is proposed to realize the synchronous tuning of frequency and circuit parameters. The experiments verified that the synchronous tuning proposed in this paper is effective, fully automatic, and more robust than the previous self-oscillating WPT system which use the TX current as the feedback variable. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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3075 KiB

Open AccessReview

Wireless Power Transfer System Architectures for Portable or Implantable Applications

by Yan Lu and Dongsheng Brian Ma

Energies 2016, 9(12), 1087; https://doi.org/10.3390/en9121087 - 19 Dec 2016

Cited by 38 | Viewed by 10358

Abstract

This paper discusses the near-field inductive coupling wireless power transfer (WPT) at the system level, with detailed analyses on each state-of-the-art WPT output voltage regulation topologies. For device miniaturization and power loss reduction, several novel architectures for efficient WPT were proposed in recent [...] Read more.

This paper discusses the near-field inductive coupling wireless power transfer (WPT) at the system level, with detailed analyses on each state-of-the-art WPT output voltage regulation topologies. For device miniaturization and power loss reduction, several novel architectures for efficient WPT were proposed in recent years to reduce the number of passive components as well as to improve the system efficiency or flexibility. These schemes are systematically studied and discussed in this paper. The main contribution of this paper is to provide design guidelines for WPT system design. In addition, possible combinations of the WPT building block configurations are summarized, compared, and investigated for potential new architectures. Full article

(This article belongs to the Special Issue Wireless Power Transfer 2016)

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