Исследование систем беспроводной передачи энергии на основе диэлектрических резонаторов и метаповерхности тема диссертации и автореферата по ВАК РФ 01.04.03, кандидат наук Сун Минчжао

• Сун Минчжао
• кандидат наук
• 2019

Оглавление диссертации кандидат наук Сун Минчжао

CONTENTS

1 Introduction

1.1 Background

1.2 Thesis arrangement

2 State-of-the-art wireless power transfer

2.1 Introduction

2.2 Classification of WPT systems

2.3 Operation principle of WPT systems

2.3.1 Coupled mode theory

2.3.2 Electric circuit theory

2.3.3. Scattering matrix method

2.4 Resonator designs

2.4.1 Coil resonators

2.4.2 Shielded loop resonators

2.4.3 PCB loop resonators

2.4.4 Summary

3 WPT based on multipole mode coupling in dielectric resonators

3.1 Introduction

3.2 Theoretical analysis of Q-factor

3.3 WPT efficiencies on MD and MQ modes

3.4 Design of the WPT system

3.5 Numerical investigation

3.5.1 Mode analysis

3.5.2 WPT efficiency on different modes

3.5.3 The influence of the loss level

3.5.4 Angular dependence of WPT efficiency

3.6 Experimental investigation

3.6.1 Experimental setup

3.6.2 Mie mode verification

3.6.3 WPT efficiency on different order of modes

3.6.4 Angular dependence of WPT efficiency

3.7 Conclusion

4 Dielectric resonators with colossal permittivity for WPT

4.1 Introduction

4.2 System design

4.3 Mode analysis

4.4 WPT performance

4.4.1 WPT efficiency with matched impedance

4.4.2 WPT efficiency in different configurations

4.4.3 Potential for high power applications

4.5 Comparison between spherical and disk resonators

4.6 Conclusion

5 Smart table based on a metasurface for WPT

5.1 Introduction

5.2 Design of WPT system

5.2.1 Concept of a smart table

5.2.2 Implementation by metasurfaces

5.2.3 Design of WPT system based on metasurface

5.3 Operation mode and frequency of the system

5.3.1 Eigenmodes of the dielectric resonator

5.3.2 Influence of L on operation modes

5.3.3 Electric and magnetic field distributions

5.3.4 Multipole expansion

5.4 WPT efficiency

5.4.1 Simulated WPT efficiency

5.4.2 Measured WPT efficiency

5.4.3 Measured WPT efficiency with optimized coupling

5.5 Safety issues

5.6 Conclusion

Conclusion

List of abbreviations

Bibliography

Appendix - Original published journal papers

Введение диссертации (часть автореферата) на тему «Исследование систем беспроводной передачи энергии на основе диэлектрических резонаторов и метаповерхности»

THESIS OVERVIEW

Relevance. A great progress of electronic industries has emerged since the end of 20th century, which has been changing the lifestyle of human being. Enjoying the modernization that various electronic devices like mobile phones, tablets, laptops, cameras and computers bring to us, however, we have to suffer the inconvenience of an increasing number of chargers and charging wires. In modern industry, a large number of compact electronic detectors and sensors are often installed in hard-to-reach places. The replacement of their power supply elements is of great difficulty. Progress in medical science in relation to critical surgeries offers patients a wide range of implantable devices. The most critical device is an artificial cardiac pacemaker, whose batteries need replace regularly. Inevitably, one more surgery would be needed to change the battery inside the body. For all these applications the ideal solution would be to deliver power to electronic devices without wires and thus avoid the batteries replacement. Fortunately, the recent progress in development of wireless power transfer (WPT) technologies open up possibilities to charge the electronic devices wirelessly.

WPT concept has a rich history and unfulfilled potential in both academic communities and commercial markets. Since the beginning of 20th century researchers have been seeking an effective way to transfer power wirelessly. As a pioneer, Nikola Tesla conducted the first WPT experiment in the early 20th century [1]. Since Tesla ran out of funds and further investments were not forthcoming, he had to stop this experiment. Moreover, his prototype was not safe and feasible due to the lack of mature radio-frequency technologies at that time. The silence of WPT research lasted until the arrival of microwave technology. In 1963, W. C. Brown demonstrated the first microwave wireless power transfer system [2]. Far-field transmission, in which the energy took the form of propagating electromagnetic waves, was thought suitable for high-power systems, such as space or military applications, where the ability to receive power wirelessly was more important than the cost of the system. However, far-field transmission is not proper for most of the devices that people interact with in daily life since the

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power transfer efficiency and the safety issue should be carefully considered [4]. Thus, power transfer through the near-field was considered as a counterpart, in which the energy can be transferred through magnetic near-field coupling (inductive power transfer (IPT)) [5] or electric near-field coupling (capacitive power transfer (CPT)) [6] between devices. In IPT and CPT systems, the power transfer efficiency can be as high as 90%, but the operation distance is only at millimeter to centimeter level [7, 8]. In 2007, a group from MIT proposed an improved IPT system based on magnetic resonance coupling between the transmitter and the receiver and the operation distance can be increased to 2 meters [9]. Nowadays, near-field power transfer become a predominant research direction.

The growing number of mobile gadgets (such as mobile phones, tablets, laptops, etc.) and the constant need to recharge their batteries make the problem of creating a contactless energy transfer system very urgent. At the moment, there are prototypes of the system of wireless energy transfer for mobile devices, but they have a number of serious shortcomings. First, it is necessary to increase the efficiency of energy transfer. Secondly, it is necessary to expand the radius of the effective transfer of energy to several meters. Third, it is necessary to reduce the intensity of the electromagnetic field in the surrounding space to values not exceeding the existing IEEE safety standards (today, in the existing experimental schemes, these values are exceeded by an order of magnitude). The elimination of these shortcomings in conjunction with successful industrialization will lead to the possibility of subsequent commercialization of such systems.

In this dissertation work several designs of WPT systems aiming at improving the power transfer distance and enabling more functionality are developed. The WPT systems based on high permittivity dielectric resonators are proposed and experimentally studied. The improvement of WPT efficiency in contrast to traditional WPT systems based on spiral coils is discussed. On the other hand, a metasurface formed by wire arrays is proposed to be used as an intermediary to enhance the near field coupling between two distant WPT resonators. In this way, the power transfer distance can be enlarged by one order of

magnitude.

The goal of the dissertation is to develop and investigate the physical mechanisms of WPT systems based on dielectric resonators and metasurface for enhanced power transfer efficiency and substantially increased transfer distance.

Scientific tasks:

1. Investigate the properties of the high permittivity dielectric resonator. Find the Mie modes and the corresponding near field distributions.

2. Investigate the coupling between different order Mie modes in the high permittivity dielectric resonators.

3. Develop a WPT system based on high permittivity dielectric spherical resonators and compare to a conventional four-coil topology.

4. Investigate the distance dependence and angular dependence of the power transfer efficiency in the WPT system based on high permittivity dielectric spherical resonators.

5. Develop a WPT system based on colossal permittivity dielectric resonators.

6. Investigate the near field properties of the cylinder resonator and find its eigenmodes.

7. Investigate the influence of distance, rotation angle and horizontal misalignment on the power transfer efficiency Of the WPT system composed of two dielectric cylinder resonators with colossal permittivity.

8. Develop a method to optimize the power transfer efficiency by tuning the coupling coefficients between different resonant objects.

9. Develop a WPT system based on metasurface formed by wire arrays. Numerically optimize the geometry of the metasurface to find an optimal design.

10. Investigate the power transfer efficiency of the WPT system as a function of the distance between the receiving and transmitting resonators placed above the metasurface. Find the maximal available power transfer efficiency by optimizing the coupling coefficients.

11. Investigate the specific absorption rate (SAR) of the electromagnetic

energy around the system through numerical simulations using a human voxel model.

Scientific novelty is specified by the following innovative results:

1. It is experimentally verified the feasibility of using high permittivity low loss dielectric resonators for WPT systems.

2. It is experimentally demonstrated the ability to realize different WPT functionalities by choosing different Mie modes of the dielectric resonator. A unique angular dependence of the WPT efficiency is obtained for the system working on the magnetic quadrupole mode.

3. It is experimentally demonstrated that the dielectric resonators with colossal permittivity can be used to further increase the Q-factor and thereby increase the power transfer efficiency.

4. A metasurface is proved to be an efficient intermediary which greatly helps increase the coupling coefficients between distant resonators and thereby increase the power transfer efficiency.

5. The safety aspect of the system based on metasurface is studied and the maximal input power under the regulation is derived for different operational frequency.

Scientific statements:

1. Resonators fabricated by dielectric material with high permittivity and low loss are experimentally verified as good candidates for wireless power transfer. As a proof of concept, WPT system based on spherical resonators made of ceramic (s = 80 + j0.008) enables power transfer efficiency as high as 80% on magnetic quadrupole mode. Near magnetic field distribution of the magnetic quadrupole mode offers multiple angles for efficient power reception, which is not available in magnetic dipole mode.

2. Resonators fabricated by colossal permittivity material (s = 1000 + j0.25) are for the first time applied to a WPT system. Compared to the high permittivity resonator, the colossal permittivity resonator has reduced

radiation losses resulting in an improved Q-factor, which enables much longer power transfer distance at a reduced operational frequency. After optimizing the coupling coefficients between colossal permittivity resonators, power transfer efficiency of 50% is experimentally obtained over the distance of 3.8 radii of the resonator at 230 MHz

3. The surface wave generated on the metasurface substantially enhances the coupling between two dielectric resonators placed above, which is an efficient way of WPT. Optimization of the coupling coefficients results in a steady efficiency profile. Power transfer efficiency of more than 80% is experimentally obtained at any distances up to 1 m (23.8 radii) between the resonators.

Practical importance of the dissertation is that the obtained results may be used for next generation of WPT systems and devices for much enlarged power transfer distance and efficiency.

Reliability and the validity of the results obtained are provided by the use of modern methods of numerical simulation and experimental research, which are comprehensively tested and widely used, as well as the correspondence of the obtained experimental results with numerical simulation data. The reproducibility of the obtained experimental results is confirmed by a series of measurements using different devices, for example VNA of Agilent and Rohde & Schwartz.

Implementation of the obtained results. The samples developed during the thesis work are used to conduct laboratory classes in the course "Technologies and Experimental Methods in Radiophysics" under the master's program "Radio Frequency Systems and Devices" and the also used as an introductory course 'Metamaterials' for the PhD program at the Faculty of Physics and Technology.

Approbation. The main results of the work were presented and discussed at the following international conferences: «Days on Diffraction» (Saint Petersburg, 2015, 2018), «International Microwave and Optoelectronic Conference» (Porto de Gelinas, 2015), «Radio and Antenna Days of the Indian Ocean (RADIO)» (Mauritius, 2015), «2016 IEEE International Symposium on Antennas and

Propagation» (Fajardo, 2016), «Progress In Electromagnetics Research Symposium» (Saint Petersburg, 2017), «The 11th International Congress on Engineered Material Platforms for Novel Wave Phenomena -Metamaterials'2017» (Marseille, 2017), «METANANO» (Vladivostok, 2017).

Publication. The main scientific results of the thesis are published 15 papers which are indexed in Scopus and Web of Science

Author contribution. The author made a decisive contribution to the choice of methods, conducting theoretical and experimental research and obtaining results, as well as the preparation of scientific publications on the results of the work.

The structure and scope of the thesis. The thesis consists of an introduction, three chapters, conclusion and list of references. The total volume of the thesis is 88 pages, including a bibliography of 100 titles. The work contains 46 drawings, placed inside the chapters.

Заключение диссертации по теме «Радиофизика», Сун Минчжао

В Заключении обобщены и приведены основные результаты работы:

1. Экспериментально подтверждено, что система БПЭ на основе сферических резонаторов из керамического материала с диэлектрической проницаемостью в = 80 + ]0,008, обеспечивает передачу мощности до 80% на частоте магнитной квадрупольной моды.

2. Распределение магнитного поля диэлектрического резонатора в ближней зоне на частоте магнитной квадрупольной моды предоставляет несколько углов для эффективного приема энергии, что недоступно на частоте магнитной дипольной моды.

3. Экспериментально и численно продемонстрировано, что максимальная эффективность системы БПЭ, равная 90%, получена для системы на основе диэлектрических дисковых резонаторов с колоссальной диэлектрической проницаемостью (в = 1000 + ]0,25). Также по сравнению со сферическими резонаторами добротность дискового резонатора увеличивается в 9 раз для магнитной дипольной моды.

4. Оптимизация коэффициентов связи элементов системы БПЭ путем настройки расстояния между ними позволяет значительно улучшить эффективность передачи энергии.

5. Предложена конструкция метаповерхности, изготовлена система БПЭ «умный стол» и выполнено экспериментальное исследование ее

характеристик. Показано, что метаповерхность поддерживает распространение поверхностной волны, которая увеличивает связь между двумя удаленными резонаторами. С использованием метаповерхности можно достичь стабильной эффективности передачи энергии до 80% при расстоянии удаления резонаторов до 1 м, когда коэффициент связи оптимален.

Основные результаты диссертации представлены в следующих публикациях:

[A1] M. Song, K. Baryshnikova, A. Markvart, E. Nenasheva, P. Belov, C. Simovski, P. Kapitanova, Smart table based on a metasurface for wireless power transfer, Physical Review Applied, 5, 054046, (2019). [A2] M. Song, P. Belov, P. Kapitanova, Wireless power transfer inspired by the modern trends in electromagnetics, Applied Physics Reviews, 4, 021102, (2017)

[A3] M. Song, P. Belov, P. Kapitanova, Wireless power transfer based on dielectric resonators with colossal permittivity, Applied Physics Letters, 109, 223902, (2016)

[A4] M. Song, P. Kapitanova, I. Iorsh, E. Nenasheva, P. Belov, "Wireless power transfer based on magnetic quadrupole coupling in dielectric resonators", Applied Physics Letters, 108, 023902, (2016). [A5] M. Song, P. Belov, P. Kapitanova, "Colossal permittivity resonators for wireless power transfer systems", Antennas and Propagation (EUCAP), 904907, (2017)

[A6] M. Song, P. Belov, P. Kapitanova, "Resonators for wireless power transfer systems", Radio and Antenna Days of the Indian Ocean (RADIO), 1-2, (2017) [A7] M. Song, P. Belov, P. Kapitanova, C. R. Simovski, "Wireless power transfer through multipole coupling in dielectric resonators", Progress in Electromagnetics Research Symposium (PIERS), 1632-1635, (2017) [A8] M. Song, P. Belov, P. Kapitanova, "Multipolar modes in dielectric disk resonator for wireless power transfer", AIP Conference Proceedings, vol. 1874, pp. 30037, (2017)

[A9] M. Song, P. Belov, P. Kapitanova, "Dielectric resonators for mid-range wireless power transfer application", Wireless Power Transfer Conference, 13, (2017).

[A10] P. Kapitanova, M. Song, P. Belov, "Experimental investigation of wireless power transfer systems based on dielectric resonators", 46th EuMC, 755-758, (2016)

[A11] P. Kapitanova, M. Song, I. Iorsh, P. Belov, "Wireless power transfer system based on ceramic resonators", Metamaterials' 2016, 151-153, (2016)

[A12] M. Song, P. Belov, P. Kapitanova, "High permittivity dielectric resonators for wireless power transfer system", 2016 IEEE International Symposium on Antennas and Propagation (APSURSI), (2016)

[A13] M. Song, P. Kapitanova, I. Iorsh, P. Belov, "Metamaterials for wireless power transfer", Days on Diffraction (DD), pp. 323-327, (2015)

[A14] P. Kapitanova, M. Song, I. Iorsh, P. Belov, "Metamaterials and resonators for wireless power transfer", Radio and Antenna Days of the Indian Ocean (RADIO), (2015)

[A15] P. Belov, M. Song, P. Kapitanova, I. Iorsh, "Application of High-Q dielectric resonators for wireless power transfer system", Microwave and Optoelectronics Conference (IMOC), 2015 SBMO/IEEE MTT-S International, (2015)

Список литературы диссертационного исследования кандидат наук Сун Минчжао, 2019 год

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