CONSTRUCTION OF A RADIOFREQUENCY WIRELESS SYSTEM FOR ELECTRIC ENERGY TRANSMISSION

Jorge Luís; Baikova Elena; Pina Joao; Meshcheryakov V.N.; Valtchev Stanimir; Melicio Rui; Grachieva Elena

УДК 621.396.6

CONSTRUCTION OF A RADIOFREQUENCY WIRELESS SYSTEM FOR ELECTRIC

ENERGY TRANSMISSION

Luís R. Jorge u'*, Elena N. Baikova 13, Joao M. Pina 12, Viktor Mescheryakov 6, Stanimir Valtchev 12,*and Rui Melicio 4'5,EI.Gracheva7

1UNINOVA-CTS, Faculty of Sciences and Technology, University NOVA of Lisbon,

Portugal,

2Department of Electrical and Computer Engineering, Faculty of Sciences and Technology, University NOVA of Lisbon, 3Departmento de Engenharia Elétrica e de Computadores, EST Setúbal, Instituto Politécnico de Setúbal, Estefanilha, Setúbal, Portugal, 4IDMEC, Instituto Superior Técnico,

Universidade de Lisboa, Portugal 5ICT, Universidade de Évora, Largo dos Colegiais 2, Portugal, 6Lipetsk State Technical University, Lipetsk, Russian Federation, 7Kazan State Power Engineering University

romba.jorge@gmail.com (Luis R. Jorge); ssv@fct.unl.pt

Abstract: ТНЕ PURPOSE. The objective of this study is to investiёgate the possibilities of longer distance resonant energy transmission applying Wireless Power Transfer (WPT) in the MHz frequency range. The planned final purpose is the energy to be transferred to all types (aerial and terrestrial) of electric vehicles (EV), mainly for the battery charging at a larger distance, compared to the normal dis-tances of WPT in use at this moment. The key to this type of High Frequency (HF) WPT system is the strong resonant inductive coupling. METHODS. This project is based on the HF power oscillations generating equipment, which original function is to generate several kW of power at MHz frequency for welding of acrylic or other plastic details. RESULTS. As a first,step, the equipment was modified to ,supply HF power for the WPT transmitter coil, instead of supplying power to the,soldering plates. The operation frequency is defined by the factory, and it is made now regulable between 8 and 14 MHz by introducing a vacuum variable capacitor. The internal powerful oscillator is based on the electronic vacuum tube ITL 5-1, a military type, capable to deliver up to 3.5 kW active power at the output. The original output had a coaxial form for,supplying finally the capacitive load of the dielectric welder. This had to be reworked and a resonant loop, i.e., a capacitively compensated transmitting coil, is now connected. The intended application of this HF system is to charge the batteries of a public transport EV, possibly during its periodic stops, while the passengers will enter and leave. CONCLUSION. The applied frequency is relatively high and the distances are larger, this system still uses the magnetic field as the energy transporter, i.e., it is a near field transmission, a non-radiating system, and is expected not to produce adverse effects on the human being's health, or to achieve a safe protection from the field.

Keywords: Wireless Power Transfer; Aerial and Terrestrial Electric Vehicles; Longer Distance Resonant Energy Transmission; Batteries Charging; Magnetic Coupled Resonator.

СОЗДАНИЕ РАДИОЧАСТОТНОЙ БЕСПРОВОДНОЙ СИСТЕМЫ ПЕРЕДАЧИ

ЭЛЕКТРОЭНЕРГИИ

Luís R. Jorge 12,*Elena N. Baikova 13, Joao M. Pina 12, Viktor Mescheryakov 6, Stanimir Valtchev 12, *Rui Melicio 45, EI.Gracheva7

1UNINOVA-CTS, Faculty of Sciences and Technology, University NOVA of Lisbon,

Portugal

2Department of Electrical and Computer Engineering, Faculty of Sciences and Technology, University NOVA of Lisbon,

3Departmento de Engenharia Elétrica e de Computadores, EST Setúbal, Instituto Politécnico de Setúbal, Estefanilha, Setúbal, Portugal,

4IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Portugal,

5ICT, Universidade de Évora, Largo dos Colegiáis 2, Portugal, 6Lipetsk State Technical University, Lipetsk, Russian Federation, 7Kazan State Power Engineering University

romba.jorge@gmail.com (Луис Р. Хорхе); ssv@fct.unl.pt

Резюме: Целью данного исследования является изучение возможностей резонансной передачи энергии на большие расстояния с применением беспроводной передачи энергии (WPT) в диапазоне частот МГц. Планируемая конечная цель - передача энергии всем типам (воздушным и наземным) электромобилей (EV), в основном для зарядки аккумуляторов на большем расстоянии по сравнению с обычными расстояниями БПЭ, используемыми в данный момент. Ключом к этому типу высокочастотной (ВЧ) системы БПЭ является сильная резонансная индуктивная связь. МЕТОДЫ. В основе этого проекта лежит оборудование для генерации высокочастотных колебаний мощности, первоначальная функция которого - генерировать несколько киловатт мощности на частоте МГц для сварки акриловых или других пластмассовых деталей. ПОЛУЧЕННЫЕ РЕЗУЛЬТАТЫ. В качестве первого шага оборудование было модифицировано для подачи ВЧ мощности для катушки передатчика БПЭ вместо подачи питания на паяльные пластины. Рабочая частота определяется заводом-изготовителем, и теперь она регулируется в пределах от 8 до 14 МГц за счет использования вакуумного переменного конденсатора. Внутренний мощный генератор построен на базе электронной вакуумной лампы ИТЛ 5-1 военного типа, способной выдавать на выходе активную мощность до 3,5 кВт. Исходный выход имел коаксиальную форму для питания емкостной нагрузки диэлектрического сварочного аппарата. Это пришлось переделать, и теперь подключен резонансный контур, то есть передающая катушка с емкостной компенсацией. Предполагаемое применение этой ВЧ-системы - зарядка аккумуляторов электромобиля общественного транспорта, возможно, во время его периодических остановок, когда пассажиры будут входить и выходить. ЗАКЛЮЧЕНИЕ. Применяемая частота относительно высока, а расстояния больше, эта система по-прежнему использует магнитное поле в качестве переносчика энергии, то есть это система передачи ближнего поля, не излучающая, и ожидается, что она не окажет неблагоприятного воздействия на человека. здоровья существа, или добиться надежной защиты от поля.

Ключевые слова: беспроводная передача энергии; воздушные и наземные электромобили; передача резонансной энергии на большие расстояния; зарядка аккумуляторов; магнитно-связанный резонатор.

Introduction

The desire to make possible the energy supply to remote consumers, led Nikola Tesla to invent and start experimenting a system that allows a transmission of electrical energy over long distances, without using cables. The history will always remember this inventor with his remarkable 235 patents [1]. The concept of the power transmission without any physical support has more than a century. Pioneering this concept, Tesla built an experimental system in Colorado in 1899. With that system he transmitted electric energy by high frequency at a considerable distance [1, 2].

With the advance of the semiconductor technologies Tesla's dream has now become reality [2, 3]. The wireless nature of this process makes it useful in environments where implementation of physical (galvanic) connection can be inconvenient, hazardous, or impossible. Particularly in the electric vehicles (EV) battery charging, the WPT shows to be very convenient [3]. The different types of the wireless power transfer are shown in Figure 1.

The different technologies used in the branches of Figure 1, are associated with the working distance and the power to be transferred between transmitter and receiver.

Nowadays, the WET has different applications in a large spectrum of human activity. For example, in order to reduce the risk of post-operative infection and patient discomfort, a Transcutaneous Energy Transfer is widely applied to wireless powering of implantable biomedical devices [4, 5]. Examples may be some left ventricular assist devices, artificial retinas and wireless neurostimulators [5]. The technology used in these applications are the inductive coupling and the magnetic resonance coupling [6].

In the applications concerning EV batteries charging, both Stationary (in a garage) or In Movement (online), the technology used is the magnetic resonance coupling, because of a lot improved efficiency [7, 8]. To exercise a long-range energy transfer, the developed technology is the Electromagnetic Waves Power Transfer (EWPT), which is still not enough mature for a practical

implementation. This technology is based on the very high-frequency energy beam, possibly transmitted from a geostationary orbital Solar Power Satellite System (SPSS) [9]. The concept was introduced by Peter Glaser in 1968, who suggested the receiver to be mounted on the Earth surface of several km2. The microwaves beam was experimented by Glaser for supplying a small flying helicopter at 200 m distance. Another idea is suggesting a Laser beam sent to the Earth a rectenna (rectifier plus antenna) system [9].

Fig. 1. Types of the Wireless Power Transfe

Рис. 1. Типы беспроводной передачи энергии.

Methods. Wireless Power System Formulation. Triode operation

The electronic tubes are constructively formed by a casing of glass, ceramic and metal, containing therein a gas (special cases) or vacuum (normally). In the first case they are called gas valves, the second type are just the normally used electronic valves. To conduct an electric current the electronic tube has at least two electrodes. The first electrode is emitting electrons [10-12]. This

is the cathode (kT ). The target electrode that attracts and receives the electrons, is called a plate ( p ) or anode ( a ).

To produce free electrons the cathode (kT) must be heated and this is done directly or indirectly. In the first case, the cathode (kT ) is heated by an electric current that passes through it. In the second case there is a heating resistance (filament), inside the cathode (kT), which stays isolated from that filament [11, 12].

For an electron to leave the surface of the cathode (kT), it is necessary to obtain the

extraction energy level, represented by . If the charge of the electron is represented by , then the extraction potential is given by:

V0 =

(1)

q0

The V0 represents the extraction potential that is used as the fundamental value for the formula given by Owen Richardson:

T (-11666v„-T )

I = KT - e o

(2)

Where IP is the anode current, here named the plate current, K is a constant that depends on the material and T is the absolute temperature in Kelvin.

The coefficient K is known mostly as Richardson coefficient AG and its approximated value is: 1.2x106 [Am-2K-2], i.e., it is a current density per absolute temperature squared.

Once the cathode (kT ) is heated, a cloud of electrons is formed, as a space charge, around the cathode (kT). The effect is known as Edison effect [12, 13]. It is concluded that the electric current depends on three factors:

The voltage applied between the cathode (kT ) and the plate; The temperature of the cathode (kT );

The distance between the cathode (kT) and the plate (anode).

Briefly, the electric current rises when the anode (a) is growing more positive in relation to the cathode (kT ) and the current goes higher also with the rising temperature and with the reduced

distance between the anode (a) and the cathode (kT). The function current/voltage known as

"two thirds", is further developed in (3). This operation, conducting at positive voltage of the plate and not conducting at negative plate voltage, is used in the simplest electron tube diode Rectifiers. Being the flux of electrons very limited, the vacuum tube diodes are far from ideal, presenting quite a high voltage drop [13, 14]. This particularity of the electron tubes obliges to use always a relatively high voltage supplied to the electronic tube circuits when the power electronics equipment is constructed.

Lee De Forest conceived the idea of introducing a third electrode in the vacuum tube. This additional element, the grid, controls the current flowing between the cathode (kT ) and the plate (p). Fig. 2 shows the triode (three terminals tube) symbol with its elements.

Cathode (kT)

Fig. 2. Triode symbol

Рис. 2. Обозначение триода.

The grid is more negative than the cathode when the valve operates as an amplifier or as a linear regulator of the electron flux. Then the grid repels some electrons. This negative grid voltage is used as a bias voltage, i.e., a fixed voltage between the grid and the cathode, when the tube is a linear regulator. The most negative grid-to-cathode voltage value that blocks completely the plate current is the cut-off voltage. Its value depends on the plate voltage [14, 15]. The plate (p) current is a function of the grid voltage, and the plate (p) voltage is given by:

I = K

p

E

E +S-

V g ^У

ч 3/2

(3)

In (3) constant K depends on the size of the valve. According to (3) the anode (a) current is only possible plate (p) when:

( E

Eg + E

V g И y

> 0

(4)

The factor ^ represents the most important parameter of the valve, the "voltage amplification", and is a constant, independent of any voltage. It depends only on the geometry of the valve [15, 16]. The maximum current could be reached if the grid would be made positive, but this is made very carefully as the grid is only capable to accept limited values of grid current. There are three static characteristics, which are essential, and characterize the valve. In the case of the tube ITL 5-1 it is declared by the producer:

Amplification factor -20 (approx.)

Grid resistance

( R )

-1250 О

Transconductance ( gm ) -23 mA/V These (differential) parameters are defined as:

Ц =

AEp

AEg

at IP = constant

g y

R =

g m

v AI, y 'AO

AE

v g

at E„ = constant

Relates the three parameters is given by: ц

gm "

R,

(5)

Fig. 3 represents the physical model of a triode, where all the "small signal" important elements that constitute a triode are shown.

p

Fig. 3. Equivalent circuit of a triode as amplifier a "small signal" approximation

с

gmVgkT

о < >Rp -

£SkT

кт

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Рис. 3. Схема замещения триода в качестве усилителя в приближении "малого сигнала "

Oscillator operation

The requirement for negative grid voltage is not valid in the case of an oscillator circuit. In this case the "amplifier" has a positive feedback.

By the positive feedback the oscillator will transform the DC supply voltage into an AC voltage output, i.e. producing oscillations. The basic principle of an oscillator is shown in Fig. 4.

PVou, A V-

в

Fig. 4. Basic principle of an oscillato

Рис. 4. Основной принцип работы осциллятора.

There are three essential conditions that an oscillator must have: Ability to self-excitation; Frequency Stability; Amplitude stability.

The equation that the circuit must obey to oscillate and have a stable oscillation is the following:

(3xi = l (6)

Here p is defined as a reaction, or the feedback factor, and is given by:

с

g

The Vis the rms value of the AC component of the plate (p) voltage and Vr is the

rms

feedback voltage. The amplification A is defined by the coefficient between the plate voltage Vp

and the grid voltage Vg , given by the relation:

V„

V,

(8)

g

The condition for which there is balance in terms of amplitude and frequency should be verified by the following equation:

- 1 1 |i gmZ

(9)

In this equation, the gain u and the transconductance g„, do not depend on the frequency.

Only Z , the impedance, depends on it. To reach the maximum Z of the load, that includes inductance L and capacitance C, the oscillators use the resonant frequency, given by:

f =

1

LC

(10)

For the HF power generator, a tuned plate (p) oscillator is used as shown in the following Fig.

5.

C05

I

#C

L01

jrm.

VT01

C03-i- <R02 N-K

Fig. 5. Schematic of the oscillator used (plate (p) tuned)

Рис. 5. Схема используемого генератора (пластина (п) настроена)

The tuned circuit determining the frequency, comprises LT and the regulable CT . The capacitor C05 and the inductance L01 serve to isolate the DC power supply from the resonant tank circuit LTCT. The biasing of the grid is done by the leakage resistance R02 and the capacitor C03.

When the generator reaches its normal operation, only a low positive current shall be allowed, and for that reason the grid current is measured. The grid bias voltage is equal to the voltage drop at the

R02 terminals. The measurement of the grid current is important for avoiding a highly positive grid

current, which is known to be dangerous to the valve and its vacuum level. Resonant circuits

The resonant processes and their parameters will be simplified in the further chapters text. The voltage source will be included with its internal impedance (resistance) into the resonant circuit. The generator voltage is presented further in series with the inductor L, as it is normally induced into the resonant inductance. In this generalized approach there are two important basic parameters that describe the resonance [17, 18].

• Resonance frequency ro0 ;

• Intrinsic loss rate (dumping factor).

The circuit of Fig. 6 represents the equivalent RLC series circuit.

L

T

C

Rs

R<

Fig. 6. RLC series circuit with an AC voltage source Рис. 6. Последовательная схема RLC с (generator) источником (генератором) переменного

напряжения

Here the Rs is internal resistance of the generator, and the resonant circuit parameters are as already defined.

Applying the Kirchhoffs Law to the circuit of Fig. 6 results in:

l (œt ) =

.sin ( œt ) = uL + uR + uC

i =

dqC dt

(11) (12)

Dividing (13) by L is given:

and:

then:

щ sin(œt) = L^f + RdqC + qC s v ' dt2 dt C

d2qC R dqC qC 1 . , -,

—rT +--2Ç + -2Ç. =—u ssin (œt )

dt2 L dt L.C L K '

œn =

JLLC

(13)

(14)

(15)

LC = Л

œo

(16)

Substituting the LC from (16) into (14) is obtained:

dt L dt The intrinsic loss rate is defined by

2L

d2qr R dqC 2 1 . , ч + T^T + ®oqc = ^sm (œt )

C= -

R

or

replacing (18) into (17):

R_ 2 L = Ç

d qC 2 dqr 2 1

—2 + ~ + ®0qr = T us sin

(œt )

dt £ dt L

The stored energy is represented by the quality factor Q, which is defined by:

(17)

(18)

(19)

1

Q =

L 1

C R R

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(21)

Coupled resonators

Figure 7 represents a coupled resonator system:

iT iR

Cr

'Rr

Z.

in

Fig. 7. Coupled resonators

Zout

Рис. 7. Связанные резонаторы

There are two possibilities to reach the maximum transferred power. The first possibility is to use a constant AC current source, the second is to use a constant AC voltage source [17, 18]. Constant AC current source

The maximum power transferred reaches the maximum point when the current in the load is maximum and is defined by:

ю MT RCR

■ X l-p

jroCRRL +1 - ro LrCr The resonant frequency is given by:

Constant AC voltage source

In the second possibility, the maximum current is given by: . jro3MTRCTCR

(22)

(23)

R ( jroCTRL +1 - ro2 LTCT ) ( jroCRRL +1 - ro2 LrCr ) - ro4M 2>RTC

The resonant frequency is given by:

x us (24)

ю0 (IR = <») =

<JLTCT + LRCR -\JLTCT + LRCR

- 2 (1 - k2 ) LTCTLRCR

д/2(1 k ) Lt CT LR CR

(25)

Wireless resonant power transfer

The series resonance can be obtained in two modes [17, 18]:

• The influence of the receiver circuit on the transmitter circuit;

• The influence of the transmitter circuit on the receiver circuit.

The Figure 8 represents the secondary (receiver) impedance reflected as Rr t into the transmitter circuit.

Rt

-aa/V-

Rs

«sT

■CT

*Rr

Fig. 8. The receiver impedance reflected into the Рис. 8. Импеданс приемника, отраженный в transmitter circuit цепи передатчика

The reflected resistance of the receiver circuit into the transmitter circuit is represented by RR T, given by:

R =

r,t

œ2M] r

(26)

In Figure 9 is represented the transmitter AC voltage source (generator) reflected on the receiver circuit.

Rr

—Wv—

Cr

'Rl

АЛЛ—

Rt,r

Fig. 9. The transmitter voltage source reflected into Рис. 9. Отражение источника напряжения the receiver circuit передатчика в цепь приемника

The reflected resistance of the transmitter circuit into the receiver circuit is, represented by R T R, is given by:

R =

лт , r

œ2MR T

(27)

And the voltage UT R is given by:

ut , r

jœM

r, t

(28)

By modifying (26) is given by:

2 j/2

R =

r,t

œ2M

R, t

Rr + Rl

The transfer efficiency is given by:

r

:

ю2 M2,rRl

(Rr + Rl ) [ю2MÏ R + (R + R ) (Rr + RL )] The mutual inductance is given by:

M = k yj LTLR

(31)

Where k is the energy coupling rate between the two coils.

The maximum transferred power PL can be achieved when the mutual inductance is fixed, and that PL is given by:

Pl =

Ю2 m2 RU2 Rl

[ю2M2,R +(Rt + R )(Rr + Rl )

(32)

Prototype Design. Proposed Wireless Power System

The Magnetic resonance coupling working in MHz frequency band is being widely considered a promising technology for mid-range transfer of a low up to a medium amount of power

[19].

The results reported in this work, are based on a factory-made welding generator manufactured by APRONECS Ltd, Bulgaria. The active element of that generator is a vacuum tube (triode) ITL 5-1, working in class C, with the following basic data of the device. Frequency up to 150 MHz Continuous wave (CW) power, up to 13 kW Plate (p) voltage up to 7.2 kV Filament voltage 6.3 V Filament current 65 A

A parallel resonance tank circuit is associated with the triode connected to its plate (p), and also named anode (a). The block diagram of the transmitter and receiver tanks is shown in Figure 10.

Transmitter LC tank Receiver LC tank Load Circuit

C,

Cr

J load ^^ R load

Oscillator

Magnetic field between Lr and Lload

Magnetic field between Lt and Lr

Fig. 10. Idealized diagram of the transmitter-receiver Рис. 10. Идеализированная схема резонансных resonant circuits контуров передатчика-приемника

Transmitter coil value determination

The measured transmitter coil inductance value is:

LT = 1,9 jiH (33)

Medhurst's [20] formula was used to calculate the value of the distributed capacitance given

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by:

C =

11,26 x I + 16r + 76,4 x.

x 10

-12

(34)

C =

11,26 x 0,11 +16x 0,4 + 76,4x .

V

|0,4

0,11

x 10 12 = 65,9 pF (35)

The available capacitor (Ct), connected in parallel with the transmitter coil is a vacuum variable capacitor, with glass encapsulation and with an adjustable capacitance between 5 pF and

2

L

100 pF . Assuming that the variable capacitor is set to the middle of its total value, the resonance frequency value is given by:

fo =

1

0 2k4lC 2^1,9 X10 6 X 115,9 x10 12

= 10,73 MHz (36)

Aiming a working frequency of 13,33MHz , it was necessary to check the available variable capacitor, has enough capacitance Ctotal to tune to that frequency.

1

C = -

(37)

C

total

2 -6 4n x 1,9 x 10

(n,33 x 106 )

2 = 75,03 pF

(38)

From this calculated value it is necessary to subtract the value of the distributed capacitance in (35), given by:

CT = 75,03 - 65,9 = 9,13 pF

(39)

Thus, the calculated value is within the possible adjustment values. Receiver coil inductance determination.

For maximum energy transfer, both resonant circuits must be tuned to the same frequency is given by:

fT fR

(40)

Where:

Lt ^C^T — -LR CR

(41)

The available capacitor for the receiver circuit is a similar vacuum capacitor, with a glass encapsulation and capacitance varying between 5 pF and 250 pF . The assumed capacitance midpoint value is 125 pF.

Replacing the values in (41) gives:

1,9 x 10-6 x 75,03 x 10-12 — Lr x 125 x 10-12

(42)

Then the calculated value is:

Lr —1,14 |H The measured value of the coil, built by the authors, was 1,2 |iH. The distributed capacitance value of this coil is given by:

C —

11,26 x l +16 x r + 76,4 x.

CRd =

V

11,26 x 0,13 +16 x 0,15 + 76,4 x

x 10

-12

(43)

V

0,15

0,13

x 10 12 — 16,2 pF (44)

The total capacitance value results from the sum of the receiver coil distributed capacitance with the midpoint value capacitance from variable capacitor.

CRt= CR + CRd =125 +16,2 = 141,2 pF (45)

The resonance frequency value determination for these L and C values gives:

1

/п =

2^1,2 х1П 6 х141,2 х1П 12

= 12,23 MHz

(46)

The values of the transmitter and receiver frequencies can be adjusted via variable capacitors. Mutual inductance value determination

The mutual inductance value is determined using the following equation.

M = kJLL

't r

(47)

Here, k is the coupling coefficient value, LT is the inductance value of the transmitter coil, the Lr is the inductance value of the receiver coil and M is the mutual inductance.

The two circuits, the receiver, and the transmitter, are tuned to the same frequency f0. Whenever k is greater than zero, the mathematical analysis shows that the two circuits, when magnetically connected, can admit two resonant frequencies f and f2, given by:

/1 =

/п л/T^k

(48)

and

/ =

/п 4ï+k

(49)

In the tests performed, the following values of f and f2 were measured: f = 8,75 MHz and f2 = 15,16 MHz .

These values make it possible to determine the value of k equal to 0,5 . Substituting the values in (47), the following mutual inductance value is given by:

M = П,5.а/1,9х 10 6 х 1,2х 10 6 = 755 nH

(50)

Prototype Implementation and Results

As mentioned previously, this work was based on an equipment, produced by the company APRONECS Ltd. Several modifications were made later to this equipment.

All the coils shown in this diagram are made of copper pipe with 12 mm outside diameter and 1mm thickness (internal diameter is 10 mm). The Figure 11 shows the real view of the transmitting coil. Figures 12 shows the transmitting coil and its adjustment bracket.

Fig. 11. Photograph of the transmitter coil

Рис. 11. Фотография катушки передатчика

Fig. 12. Photograph of the connected adjustable Рис. 12. Фотография подключенной регулируемой transmitter coil катушки передатчика

The Figure 13 shows the receiver unit.

Fig.13. The receiver unit (in the center) Рис.13. Приемный блок (в центре)

The Figure 14 shows the receiver unit with more details.

Fig. 14. The detailed image of the receiving unit Рис. 14. Детальное изображение приемного

устройств

Figure 15 shows an image taken during the final tests. It shows a 40 W lamp lit with the energy transmitted through the WPT system. The distance between the transmitting coil and the

receiving coil is 1,5 m. The working frequency that allowed the system to be optimized was 8,461 MHz on the transmitting circuit and 8,426 MHz on the receiving circuit.

Fig. 15. An image obtained in the final tests, 40W Рис. 15. Изображение, полученное в финальных lamp (author'sphoto) тестах, лампа 40Вт (фото автора)

Results

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Figure 16 shows the voltage waveforms at the transmitting tank circuit (at the inductor). The scale voltage is 2.0 kV, so the peak is 8 kV.

Fig.16. Voltage waveforms of the transmitting tank Рис.16. Осциллограммы напряжения цепи circuit (the inductor terminals) передающего бака (клеммы индуктора)

Figure 17 shows the voltage signal to the receiving tank circuit terminals. The peak voltage is 200 V.

Fig. 17. The voltage waveform at the receiving tank Рис. 17. Осциллограмма напряжения в цепи circuit (the inductor terminals) приемного бака (выводы индуктора).

Conclusions

The wireless power system presented was built based on a high-power high-frequency electronic tube oscillator. This oscillator has a triode valve as its central element. At a distance of 1,5 m it was possible to light a 40 W lamp. The main difference to the currently constructed systems is that it presents a transmitter based on vacuum tube oscillator. A necessary rectifier for

battery charging was also experimented, implemented on silicon carbide (SiC) Schottky diodes. In [21], authored by George I. Babat, some more details could be found from his experiments during 1940s in Moscow, mainly in the metro lines. In the publications in Russian language during 1942 and after 1942, he claims more than 60% of efficiency by electronic valve generators for propulsion of electric vehicles online (during their movement).

Acknowledgments: Portuguese Foundation for Science and Technology (FCT) and CTS, project UIDB/00066/2020.

References

1. Marc J. Seifer, Nikola Tesla and John Jacob Astor, 6th International Symposium Nikola Tesla, October 18-20, 2006, Belgrade, SASA, Serbia.

2. Thomas Commerford Martin. The Inventions, Research and Writings of Nikola Tesla. The Electrical Engineer, New York, D. Van Nostrand Company, 1894.

3. Steve Taramovich. Nikola Tesla and Wireless power Future. EDN Netework, September 29, 2014.

4. Sheik S.Mohammed, Professor K. Ramasamy, Professor T. Shanmuganantham. Wireless Power Transmission. A Next Generation Power Transmission System. Journal of Computer Applications (0975-8887) V. 1(13).

5. Vilathgamuwa DM. and Sampath JPK. Chapter 2 - Wireless Power Transfer (WPT) for Electric Vehicles (EVs)-Present and Future Trends. Springer Science+Business Media Singapore 2015, S. Rajakaruna et al. (eds.), Plug In Electric Vehicles in Smart Grids, Power Systems. doi: 10.1007/978-981-287-299-9_2.

6. Brown WC, Mims JR. and Heenan NI. An Experimental Microwave-Powered Helicopter. 1965 IEEE International Convention Record.1965;13(5):225-235. doi: 10.1109/IREC0N.1965.1147518.

7. Yukio Yokoi, Akihiko Taniya, Masaki Horiuchi, Shigeru Kobayashi. Development of KW class Wireless Power Transmission System for EV Using Magnetic Method. Naganao Japan Radio Co, Ltd, 1st International Electric Vehicle Technology Conference.

8. Lee S.and Lorenz R.D. A design methodology for multi-kW, large airgap, MHz frequency, wireless power transfer systems, 2011 IEEE Energy Conversion Congress and Exposition, Phoenix, AZ, USA, 2011, pp. 3503-3510, doi: 10.1109/ECCE.2011.6064242.

9. Geoffrey A. Landis. Re-evaluating Satellite Solar Power Systems for Earth, NASA John Glenn Research Center, IEEE 4th World Conference on Photovoltaic Energy Conversion, Waikoloa, HI, May 7-12, 2006.

10. Ivan Cohen, Thomas Helie. Measures and models of real triodes, for the simulation of guitar amplifiers. April 2012, https://www.researchgate.net/publication/281075913.

11. Jose Ignacio Dominguez Simon. Introduction to design with electron tubes. ISBN: 9781549714184 September 2017, https://www.researchgate.net/publication/319877861.

12. Preece W.H. On a Peculiar Behaviour of Glow-Lamps When Raised to High Incandescence, Proc. R. Soc. London. 38 219-230 (1884).

13. Jyri Pakarinen, David T. Yeh. A Review of Digital Techniques for Modeling Vacuum-Tube Guitar Amplifiers. Computer Music Journal. 33:2, pp. 85-100, Summer 2009, 2009 Massachusetts Institute of Technology.

14. Nik Glazar. Construction and enhancement of stereo vacuum tube amplifier with precision machined enclosure. https://www.researchgate.net/publication/304162099, May 2010.

15. Morgan Jones. Valve Amplifiers. Third Edition 2003, Newnes, ISBN: 0 7506 56948.

16. Jerry C. Whitaker. 13 Mar 2012. Vacuum Tube Principles from: Power Vacuum Tubes, Handbook CRC Press, Accessed on: 15 Mar 2021, https://www.routledgehandbooks.com/ doi/10.1201/b11758-4.

17. Zarko Martinovic, Martin Dadic, Roman Malaric, Zeljko Martinovic. Wireless Resonant Power Transfer - An overview, MIPRO 2016/CTI.

18. Leyh GE. and Kennan MD. Efficient wireless transmission of power using resonators with coupled electric fields, 2008. 40th North American Power Symposium, Calgary, AB, Canada, 2008, pp. 1-4. doi: 10.1109/NAPS.2008.5307364.

19. Leyh G. E. and Kennan M. D. Efficient wireless transmission of power using resonators with coupled electric fields, 2008 40th North American Power Symposium, Calgary, AB, Canada, 2008. pp. 1-4, doi: 10.1109/NAPS.2008.5307364.

20. David W Knight, The self-resonance and self-capacitance of solenoid coils: applicable theory, models and calculation methods. Updated version 2016, D0I:10.13140/RG.2.1.1472.0887.

21. George I. Babat, Electrodeless discharges and some allied problems. Journal of the Institution of Electrical Engineers. Pt III: Radio and Communication Engineering, 94(27), pp. 27-37, 1947, doi:10.1049/ji-3-2.1947.0005.

Authors of the publicftion

Luís R. Jorge - UNINOVA-CTS, Faculty of Sciences and Technology, University NOVA of Lisbon, Portugal, Department of Electrical and Computer Engineering, Faculty of Sciences and Technology, University NOVA of Lisbon.

Elena N. Baikova - UNINOVA-CTS, Faculty of Sciences and Technology, University NOVA of Lisbon, Portugal, Departmento de Engenharia Elétrica e de Computadores, EST Setúbal, Instituto Politécnico de Setúbal, Estefanilha, Setúbal, Portugal.

Joao M. Pina - UNINOVA-CTS, Faculty of Sciences and Technology, University NOVA of Lisbon, Portugal, Department of Electrical and Computer Engineering, Faculty of Sciences and Technology, University NOVA of Lisbon.

Viktor N. Mescheryakov - Lipetsk State Technical University, Lipetsk, Russia.

Stanimir Valtchev - UNINOVA-CTS, Faculty of Sciences and Technology, University NOVA of Lisbon, Portugal, Department of Electrical and Computer Engineering, Faculty of Sciences and Technology, University NOVA of Lisbon.

Rui Melicio - IDMEC, Instituto Superior Técnico, Universidade de Lisboa, Portugal, ICT, Universidade de Évora, Largo dos Colegiais , Portugal.

Elena I. Gracheva - Kazan State Power Engineering University, Russia.

Литература

1. Marc J. Seifer, Nikola Tesla and John Jacob Astor, 6th International Symposium Nikola Tesla, October 18 - 20, 2006, Belgrade, SASA, Serbia.

2. Thomas Commerford Martin. The Inventions, Research and Writings of Nikola Tesla. The Electrical Engineer, New York, D. Van Nostrand Company, 1894.

3. Steve Taramovich. Nikola Tesla and Wireless power Future. EDN Netework, September 29,2014.

4. Sheik S.Mohammed, Professor K. Ramasamy, Professor T. Shanmuganantham. Wireless Power Transmission - A Next Generation Power Transmission System. Journal of Computer Applications (0975-8887) V. 1(13).

5. Vilathgamuwa DM. and Sampath JPK. Chapter 2 - Wireless Power Transfer (WPT) for Electric Vehicles (EVs)-Present and Future Trends. Springer Science+Business Media Singapore 2015, S. Rajakaruna et al. (eds.), Plug In Electric Vehicles in Smart Grids, Power Systems. doi: 10.1007/978-981-287-299-9_2.

6. Brown WC, Mims JR. and Heenan NI. An Experimental Microwave-Powered Helicopter. 1965 IEEE International Convention Record, V. 13, Pt 5, pp. 225-235. doi: 10.1109/IRETON.1965.1147518.

7. Yukio Yokoi, Akihiko Taniya, Masaki Horiuchi, Shigeru Kobayashi. Development of KW class Wireless Power Transmission System for EV Using Magnetic Method. Naganao Japan Radio Co, Ltd, 1st International Electric Vehicle Technology Conference.

8. Lee S.and Lorenz R.D. A design methodology for multi-kW, large airgap, MHz frequency, wireless power transfer systems, 2011 IEEE Energy Conversion Congress and Exposition, Phoenix, AZ, USA, 2011, pp. 3503-3510, doi: 10.1109/ECCE.2011.6064242.

9. Geoffrey A. Landis. Re-evaluating Satellite Solar Power Systems for Earth, NASA John Glenn Research Center, IEEE 4th World Conference on Photovoltaic Energy Conversion, Waikoloa, HI, May 7-12,2006.

10. Ivan Cohen, Thomas Hélie. Measures and models of real triodes, for the simulation of guitar amplifiers. April 2012, https://www.researchgate.net/publication/281075913.

11. Jose Ignacio Dominguez Simon. Introduction to design with electron tubes. SBN: 9781549714184 September 2017, https://www.researchgate.net/publication/319877861.