ANALYSIS ON EFFICIENCY OF WIRELESS POWER TRANSFER USING HTS COIL

OverviewHistory of WPT

Resonance inductive coupling

Theortical approach

Experimental Setup

Different cases

Major losses

Advantages and disadvantages

Future research

Conclusion

References

Wireless electricity way

back in the 1800s……..

In the year 1891,Nikola Tesla proposed the method of wireless transmission of electric power

One of the greatest breakthroughs of science at that time

Built the wardenclyffe

tower which could

broadcast power

wirelessly,is called off as it

radiated power into

surroundings raising issues

of

•Power theft

•Health concerns

The Wardenclyffe Tower

A dream crashes……

Resonance Inductive Coupling(RIC)

The capacitor and inductor forms the resonator. Charge oscillates between inductor (as magnetic field) and capacitor (as electric field.)

•This type of oscillation is called resonance if the reactance's of the inductor and capacitor are equal.

CONVENTIONAL SYSTEM

HIGH TEMP SUPER CONDUCTORThe electrical resistivity of a metallic conductor decreases

gradually as temperature is lowered and at the same time its

conductivity becomes infinity.

• BSCCO needs to be hole-doped by an excess of oxygen

atoms in order to superconductor.

• By changing the oxygen content Tc can thus be altered at

will. 

•  Even though BSCCO has a higher upper critical field than

YBCO due to some variations in chemical composition,

YBCO are preferred to BSCCO though they are much more

difficult to fabricate.

• Experimental setup

Theoretical approach

Couple mode theory The wireless power transfer can be presented as a set of

first order linear differential equationsAssumptions

• Internal loss of coils is comparatively small.

• Frequency range of operation is narrow enough to assume

inductance and internal capacitance of the coils be

constant.

Circuit model

Assumption

• Transmitting and receiving coil should have same

resistance and inductance.

• The coupling capacitors,should be such that both

capacitors must have the same rating at resonant

condition.

Experimental setup

• Superconductors preferred :BSCCO (Bismuth

Strontium Calcium Copper Oxide).YBCO (Yttrium

Barium Copper Oxide)

• Shape : corresponds to a ribbon which can be

wound easily can also be used.

• Treated with liquid nitrogen to enhance the

thermal stability.

• Kapton tape is used as insulation between HTS

tapes when winding the coils.

• Then AC power is supplied.

• The capacitor used can be also made of

superconducting material .

• External capacitance provided to lower the

operating frequency and to attain high efficiency

and large distance transmission.

• Booster resonator coil can be positioned between

the primary and secondary coil for large transfer

distance.

• Frequency range selection for eliminating

radiative loss.

Different case for frequency 1.4KHz to 4.3KHz

• HTS coil (as transmitting coil) to HTS coil (as

receiving coil) at 77 K

• copper coil to copper coil at 77 K

• copper coil to copper coil at RT

• copper coil at RT to HTS coil at 77 K

• copper coil at 77 K to HTS coil at 77 K

• HTS coil at 77 K to copper coil at RT

• HTS coil to copper coil at 77K

• The resistances of the coils were measured by

RLC testing consist of 2 parts:

• ac losses in HTS coils device. The resistances of

HTS coils

• AC losses in the HTS coils contain 3 parts.

The Transport Loss

The Hysteresis Loss Caused by Magnetic Field

The Eddy-Current Loss

Main losses..

To reduce the losses…

• Use superconducting material

• Lower the operating frequency

Inference

Deviation in the graph

because the transport

current becomes

higher near the resonant

frequency, and ac losses

of HTS coils

cannot be neglected

under such condition.

At transfer distance of 6.5

cm

1) 92.78%

2) 53.47%

3) 27.07%,

At transfer distance

of 11cm

 1)68.73%

2) 62.28%

3) 34.05%

4) 24.58%

• The maximum power transfer efficiency at 11 cm of a WPT

system with HTS coil as transmitting coil is 2.5 times higher

than that of a WPT system with HTS coil as receiving coil.

Hence, HTS coils are more suitable for being as a

transmitting coil than as a receiving one.

Advantage Disadvantage

• Transfer Efficiency Will Be

More Compared To Copper Coil

• HTS coil can be used as

transmitting coil for higher

efficiencies

• Booster resonator coil can be

placed between the

transmitter and receiver coil

for long distance transmission.

• Capacitance is added inorder

to reduce radiative losses and

to maintain the coil in

resonance.

• Operating frequency can

be decreased within a

specific range.If not,it

will affect the power

transfer efficiency.

• Frequency below 1MHz

preferably 200KHz is

applicable for power

transfer in the present

system.

Conclusion

• Simulation results concludes that HTS coil can

give high efficiency and can be transmit power to

larger distance by placing a booster resonator.

• Transfer efficency will be high if the HTS coil is

used as transmitting coil.

Future research

Wireless power transmission can be done by

• employing different coil shapes.

• adding intermediate coils.

• Using low temperature capacitors or HTS

capacitors.

• Situations where we have to sign in to a power

zone to charge the devices.

Reference

• GuoMin Zhang, Hui Yu, Liwei Jing, Jincheng Li, Qi Liu, and

XianghuaFeng ‘Wireless Power Transfer Using High Temperature

Superconducting Pancake Coils’IEEE TRANSACTIONS ON

APPLIED SUPERCONDUCTIVITY, VOL. 24, NO. 3, JUNE 2014

• Senthil Nathan.M1, Pandiarajan.K / International Journal of

Engineering Research and Applications (IJERA) ISSN: 2248-9622

www.ijera.com Vol. 3, Issue 1, January -February 2013, pp.1125-

1130 1125 |P a g e A Review Of Wireless Power Transmission

• T. Nakamura *, K. Higashikawa, I. Muta, A. Fujio, K. Okude, T. Hoshino

‘Improvement of dissipative property in HTS coil i`mpregnated with

solid nitrogen’ Department of Electrical Engineering, Graduate School

of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo, Kyoto 606-

8501, Japan :www.sciencedirect.com

• Alexey Bodrov and Seung-Ki SulIEEEFellow,Republic of Korea “Analysis

of Wireless Power Transfer by Coupled Mode Theory (CMT) and

Practical Considerations to Increase Power Transfer Efficiency”

 

• RAYMOND J.SEDWICK UNIVERSITY ARK ,MD (US)”Methods and system

for long range wireless power transfer” United States Patent

Applicationpublication.Pub:US 2012/001079 A1:Pub date:Jan 12,2012

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