Reconfigurable Wireless Power Transfer Systems With High Energy Efficiency Over Wide Load Range (original) (raw)
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Design and Analysis of Resonant Wireless Power Transfer System
MATEC Web of Conferences, 2018
In this paper, the modelling and analysis of resonant wireless power transfer (RWPT) system are carried out by using circuit theory. Equations of the efficiency and frequency are derived for basic series-series circuit topology and series-parallel-mixed circuit topology. The designed model uses the series-parallel-mixed topology. The model is tested for two different peak-to-peak voltage levels including 20 V and 40 V. The achieved efficiency at 20 V is 49.10% and at 40 V is 49.52% approximately. The modelling is performed by using advanced design system (ADS) high frequency design software. In addition, an overview of currently available wireless power transfer (WPT) technologies and the recent study on inductive wireless power transfer (IWPT) and resonant wireless power transfer (RWPT) systems is also presented.
IEEE Transactions on Power Electronics, 2018
Maximum energy efficiency in wireless power transfer (WPT) systems can be achieved through the use of magnetic resonance technique at a certain load resistance value. However, practical load resistance is not constant. Previously, a switched mode dc-dc converter was used in the receiver circuit to emulate an equivalent load resistance for maximum energy efficiency. In this paper, a new approach based on the On-Off Keying is proposed to achieve the high energy efficiency operation over a wide range of load power without using an impedance-matching dc-dc power converter. This simple and effective method has reduced average switching frequency and switching losses. It can be applied to any series-series resonant WPT system designed to operate at a constant output voltage. Practical measurements have confirmed the validity of the proposal.
Advanced Optimization Circuit for Wireless Power Transfer
The wi-fi energy transfer (WPT) is an emerging era with increasingly more ability packages to transfer energy from a transmitter to a cellular receiver over a noticeably huge air gap. but, its extensive utility is hampered due to the relatively low performance of modern wireless power switch (WPT) structures. This study gives an idea to maximize the performance in addition to to increase the quantity of extractable electricity of a WPT system operating in resonant operation. The proposed method is primarily based on actively modifying the equal secondary-side load impedance by controlling the section-shift of the active rectifier and its output voltage degree. The offered hardware prototype represents an entire wireless charging machine, consisting of a dc–dc converter that is used to price a battery at the output of the system. Experimental results are shown for the proposed concept in comparison to a traditional synchronous rectification approach. The supplied optimization technique sincerely outperforms trendy solutions in phrases of efficiency and extractable power.
Investigation of correlation of design parameters in wireless power transfer system
IET Science, Measurement & Technology
Achieving higher power transfer efficiency with permissible output load power is a formidable challenge in designing a magnetically coupled resonant wireless power transfer system. Consequently, to instigate the power transfer characteristics, the theoretical models based on reflected load theory as well as lumped circuit models have been employed, which have been substantiated with the experimental measurements. It has been apprehended that maximum efficiency as well as the power delivered to the load can be enriched from the depreciated value through appropriate deliberation of coil's quality factor (coil design dependent) and coupling coefficient with acceptable operating frequency under different electric load conditions. The obtained results illuminate the correlation between the maximum power transfer ability and the quality factor of the coils, as well as the coupling coefficient, under different electric load conditions. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
High Efficiency with Small Coils Area Ratio of Magnetic Resonant Wireless Power Transfer System
European Journal of Electrical Engineering and Computer Science, 2018
Wireless power transfer using magnetic resonance requires cutting flux lines generated from the transmitter coil by the receiver coil. This letter shows that an exact one to one coil area ratio or CAR (i.e. primary relative to secondary) is not a pre-condition to obtain high efficiency. It is also shown that high efficiency can be achieved for relatively small CARs by adjustment of the turns ratio. We go on to show that it is possible to achieve a higher energy efficiency than the coil area ratio and the associated flux cut would dictate.
IEEJ Journal of Industry Applications, 2018
Recently, the dual transmitting resonator wireless power transfer system (DTR-WPT) has been proposed as a promising technique for the power supply of mobile apparatus. Although this technique has been reported to be effective for increasing the output power as well as for covering a wide area during wireless power transfer, the complicated magnetic coupling among two transmitting resonators and one receiving resonator makes it difficult to develop practical design optimization methods, thus hindering practical applications of this technique. The purpose of this paper is to propose a design optimization method for the load impedance of DTR-WPT. This method is derived based on a novel simple equivalent circuit model of the DTR-WPT. The optimum impedance derived using this method as well as the appropriateness of the equivalent circuit were verified experimentally, thus validating usefulness of the proposed method for the practical application of DTR-WPT.
IEEE Transactions on Industrial Electronics, 2000
Wireless power technology offers the promise of cutting the last cord, allowing users to seamlessly recharge mobile devices as easily as data is transmitted through the air. Initial work on the use of magnetically coupled resonators for this purpose has shown promising results. We present new analysis that yields critical insight into design of practical systems, including the introduction of key figures of merit that can be used to compare systems with vastly different geometries and operating conditions. A circuit model is presented along with a derivation of key system concepts such as frequency splitting, the maximum operating distance (critical coupling), and the behavior of the system as it becomes under-coupled. This theoretical model is validated against measured data and shows an excellent average coefficient of determination (R 2 ) of 0.9875. An adaptive frequency tuning technique is demonstrated, which compensates for efficiency variations encountered when the transmitter to receiver distance and/or orientation are varied. The method demonstrated in this paper allows a fixed-load receiver to be moved to nearly any position and/or orientation within the range of the transmitter and still achieve a near constant efficiency of over 70% for a range of 0-70 cm.
IEEE Access
This paper offers a new EF-class converter for dynamic wireless power transfer application. The proposed high-frequency converter employs a floating-frequency switching algorithm to control the converter in a continuous frequency range, eliminate the requirement to any additional operational data from the secondary (receiver) side, accelerate the load impedance match while moving, maximize the transferred power rate, reduce charging interval and compensate power transfer tolerances. Moreover, an optimized super elliptical shape coil is designed to cope with lateral misalignment, enhance coil coupling, and increase efficiency. In the proposed converter, (i) soft switching is implemented to increase switching frequency, decrease passive components size, and improve power density, (ii) undesired voltage harmonics are attenuated to reduce peak voltage stress of the power switch in a wide frequency range, (iii) the receiver side is enabled for higher mobility with stable power transfer, and (iv) the resonant frequency is updated to compensate nonaccurate values of passive components in experimental prototyping. In this study, the operational analytics, compensation method, control algorithm, coil design and converter optimization are followed with some comparisons to present the converter capabilities. In addition, simulation and experimental results are provided under different degrees of misalignment to verify the accuracy of theoretical analytics. INDEX TERMS EF-class resonant converter, floating-frequency switching algorithm, coil shape optimization, dynamic wireless power transfer.
Aeu-international Journal of Electronics and Communications, 2019
This paper is a thorough theoretical analysis of a two-coil wireless power transfer system (WPTS) configured in series with a focus on power optimization rather than maximizing transmission (link) efficiency. Different definitions of the system efficiency in the pertaining literature are distinguished and clarified. The frequency splitting phenomenon is precisely explained, and furthermore, the analytical solutions are derived based on analysis of the input impedance. The effects of this behavior on the power transfer to a load resistance are discussed. Various aspects of the power optimization problem are explored. In particular, for the case when the system is driven at the resonance frequency, (i) the explicit expression of the optimal coupling factor between the two coils for a given load, and (ii) the optimum power with respect to the load are provided. The impedance matching methods using different circuit topologies are analytically or numerically investigated, revealing that the drive frequency can be arbitrarily chosen and not necessarily equal to the resonance frequency. This provides more options for exciting the system apart from the resonance condition, without compromising the delivered power. A comparison between optimization techniques is given in terms of the coupling factor k, showing that the bi-conjugate matching with Π − networks results in the maximum generated power and the transducer power gain (i.e., defined by the ratio between the received power and the power available from the source), which reaches 80 % at k = 84.4 × 10 −3 , for example.
Progress In Electromagnetics Research M, 2020
Accomplishing high efficiency with acceptable output load power is a formidable design challenge in resonant wireless power transfer (WPT) system employed for charging Electric Vehicle (EV). This necessitates a trade-off among the assorted parameters like coil quality factor, coupling coefficient, and electric load for performance enrichment of resonant WPT system. It is realized that the high value of quality factor does not ensure higher power transfer efficiency, but it is largely influenced by the electric load. For each coupling coefficient there exists an optimum load for which maximum power can be delivered. It is also perceived that for a fixed vertical separation gap of the coils, increasing receiver coil quality factor has no profound effect on the output load power as well as efficiency. The circuit model based analytical results agree well with the comprehensive experimental ones and elucidate the strategic design guidelines for a competent wireless electric vehicle charging system.