Wireless Charging Technology of Electric Vehicle

Wireless Charging Technology of Electric Vehicle

! School of Electrical Engineering, Southeast University ! Dr. Huang Xueliang Mobile：13770520753 Email：[email protected]

CONTENT

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Reasons to develop wireless charging technology

Key technology to be explored and realized

Major facilities related to wireless charging

Ways to realize wireless charging

5 Demonstration platform of Southeast University

6 Summary and Outlook


•  the main business model of electric vehicles’ wired charging: charging station mode, charging pile mode and replacing battery model

• Wired charging of electric vehicle ——Slow charging AC charging : Voltage 220V or 380V, current about 15A; For 35Kwh battery pack, usually takes 6-8 hours to be fully charged per time；A charging position one day can charge three cars ; if on average an electric car needs to be charged every three days, a charging station has 10 positions, up to 2015, 500,000 Electric vehicles -55,000 charging stations ;up to 2020, 5,000,000 Electric vehicle -55,0000 charging stations

More exclusive charging stations, more areas!

5-year –10 times’ expansion ,more difficult!


AC charging : once-about10-20 minutes; 10minutes-needs 250kW power, 5 times of an office building electricity load; A charging station with four battery chargers, power will be able to reach "MW" grade, what a problem! Presumably, up to 2020, one large city owns 300,000 electric vehicles to be charged every 3 days; Luckily, about 20%, that is, 20,000 electric vehicles are quickly charged, evenly distributed throughout 10 hours during the daytime, new load about 100Mw added; worst case -occurs in the rush hours, new load about 500Mw added.

Big shock Impact on the grid

845 February 2012, maximum daily

load of NanChong

700 April 2012,

maximum daily load of

ShangYu 100

500

0 100 200 300 400 500 600 700 800 900

1 2 3 4 5

Comparison new load with maximum daily load of city

additional load of quick charging

Idea

lly


• Electric vehicle Wired charging——quick charging

Mw

Battery replacing- needs a short period of time- guarantee the car use; However, problems lie in the following aspects-standardization of battery , economic problem of large-capacity battery , determination of old or new battery pack. The impact of battery on the environment must be considered as an important issue, too!

Problem of standardization,

Impact on Environment


• Electric vehicle Wired charging——battery replacing

• Characteristics of wired charging Electric vehicle

Advantages

Completed theories, mature technology, low cost, easy to accept

Disadvantages

inconvenience, poor security, management difficulties; more land occupation, high demand for batteries, large impacts on the grid

Other charging ways?



§  Fundamentals in wireless charging system of electric vehicle

Electric vehicle wireless charging system consists of energy transmitting devices under the cars and energy receiving device in the cars, the energy can be transformed wirelessly from the transmitting device to the battery.

Garage

Community

Large parking lot Roadside

l  The main forms of electric vehicles wireless charging ：Distributive 、 Mainly slow charge . Basic fact: 1.Private vehicles are parked in the parking spaces for 90% of the time .

l  2. After electric vehicles are large-scale, power grid can not afford the mode of quick charging.


• Advantages of electric vehicles wireless charging

C o n v enience

Electric vehicle can be charged automatically, so users can remotely control the charging process via mobile phones and other devices, enhance the user experience.

L e s s area

Charging coil is buried directly beneath the original parking or the existing road without the need of additional land and space occupation, effective use of land resources.

S a f e t y , reliability

No cable aging, leakage and other issues. Simply programmed to automatically charging, reduce human management，no magnetic affect.

• Other advantages? ?


Wireless charging electric vehicles have bigger interaction ability with the grid than wired charging electric vehicles

Electric Vehicle access network technology is an important part of the “Smart grid technology” - the energy can be exchanged in two-way interaction between the grid and electric vehicles . The bigger interaction ability , the more positive effects on the smart grid.

Probability in charging

position

probability of a physical connection to the grid

probabilities of Interactive

willingness selection

probability of the electric

vehicles interactive

with the grid

Daily interaction ability of electric vehicles at Nanjing in 2020

Maximum interactive capacity

forecasting（Mwh）

Maximum interactive power prediction（Mw）

Wired 30% 90% 35% 9.45% 1587.6 158.76 Wireless 80% 100% 80% 64% 10750 1075


Information, intelligence, reduce labor

costs

actualize the role as a movable

accumulator

Automatic charging; multiple charging

Reduce the battery capacity

requirements

Load shifting, reducing the

impact on grid

Convenient, safe and reliable

Effective use of land

resources

Suppression of renewable

energy output fluctuation

Benefits


With the rapid development of the world's electric vehicle industry and electric vehicle wireless charging technology, the electric vehicle wireless charging is an important developmental direction in the future!


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2 Electromagnetic resonance wireless charging

1 Electromagnetic induction wireless charging

3 Microwave wireless charging

4 Electric field coupling wireless charging

! Separate the primary and secondary side is the basic feature of inductively coupled power transmission circuit. There is a gap between primary circuit and secondary circuit, which are connected via strongly coupled magnetic resonances.

Electromagnetic induction wireless charging Ways to realize wireless charging

Electromagnetic induction wireless charging touring bus

Through cooperation with enterprises, UOA designed a touring bus, using inductively coupled power transmission technology for charging

GM EV1 Electric Vehicle


Electromagnetic resonance wireless charging WiTricity’s technology is raised by MIT and the researchers of Institute for Soldier Nanotechnologies. The system uses two same frequency resonant objects to produce strong mutual coupling, forming the resonant circuit, the energy in the interaction between two objects, using coil and placed at the ends of the plate condenser, to realize the wireless transmission of energy.


With cooperation with Mitsubishi and IHI, Witricity has designed the electric vehicle charging device: 3.3 KW of output power, 20cm transmission distance, efficiency is 90%.

WiTricity’s technology in Electric Vehicle Ways to realize wireless charging

The research group of Southeast

University in China has developed ：

the first set of electromagnetic

resonance electric vehicle charging

system, the first electric vehicle of

wireless charging.


Microwave wireless charging Convert the electrical energy into microwave energy through the magnetron, send the microwave beam by the transmitting antenna, turn the microwave energy into the electrical energy through the rectifying device after receiving antenna.

Electric Vehicle with Microwave wireless

charging


Electric field coupling wireless charging Electric field coupling ： Set electrode in the power supply part and receiving part respectively, using the electric field between the two electrodes to transmit power. Also called capacitive coupling.

ail transportation

At present the technology is mainly applied in the wireless charging of small electronic products . The application of electric field coupling wireless transmission technology in the electric vehicle or ail transportation is at development stage.


Type power distance features

Electromagnetic induction kW cm

high transmission efficiency, short transmission distance, between the secondary coil and receiving circuit must be shielded, eddy current heating phenomenon happens around the metal .

Electromagnetic resonance kW m

small radiation, directional; The medium distance transmission, high transmission efficiency , The energy transfer is not affected by space obstacle, eddy current heating phenomenon not happen around the metal, transmission distance, and power efficiency are sensitive to relative frequency.

Microwave kW m

long transmission distance, the higher frequency, the greater transmission energy; very small loss of the energy transfer in the atmosphere, energy transmission is not affected by gravity difference; easy to interfere communication, influence on organism; energy beam hard to concentrate, big scattering loss, poor directional and low transmission efficiency.

Electric field

coupling kW mm, cm

high transmission efficiency, short transmission distance, small electromagnetic interference, possible for highly convenient wireless charging system; Electrode part no heat.


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wireless charging -the key technology

The optimization method of Transfer efficiency

Analysis of system topology effect

High-frequency power supply and rectifier technology

Load matching technology and minimal access technology

1、 The analysis of system topology effect MR1

i1Us

C1

Rs

L1

R2

RLL2

C2

i2

MR1

i1UsC1

Rs

L1

R2

RLL2C2

i2

MR1

i1Us

C1

Rs

L1

R2

RLL2C2

i2

MR1

i1UsC1

Rs

L1

R2

RLL2

C2

i2

Power efficiency comparison of the same system under different topologies

Four kinds of topologies


Several scheme of H

igh-frequency power

High frequency inverter

Double tube high frequency resonant E class

High-frequency oscillation power

M i c r o S i g n a l p o w e r amplification

2、High-frequency power supply and rectifier technology

A d v a n t a g e ： h i g h -frequency, high-power　　　　　　　　　　　　　　　　 D i s a d v a n t a g e ：L o w ef f ic iency, h igh heat d i s s i p a t i o n； p o o r frequency adjustability

Advantage:High efficiency，Implementation method is relatively mature Disadvantage：Difficult to simultaneously achieve high-frequency and high-power

Our team established high frequency adjustable power supply system based on the oscillation and inverter，compare the pros and cons of the two in system frequency tracking, matching, efficiency optimization and stability and other aspects , determine the different requirements of high-frequency power in different application environments。


High-frequency rectifier：Solve problems such as the

frequency stability, the adjustment of the output

power and cooling device, optimization problems; the

minimum access technology and the transmission

system are realized based on system load

characteristics.

Developed by our team, the 2-3 kW high frequency

rectifier regulator device, based on the frequency

tracking and self-tuning technique, can realize

stable output voltage under high frequency power。

2、High-frequency power supply and rectifier technology


distance vs. efficiency Load power vs. frequency

3、 The optimization method of Transfer efficiency

Transfer efficiency has always been one of the most noteworthy in WPT. Generally, the closer the transmission distance, the greater the device volume, the higher the transmission efficiency is, the greater the transmission power. How to improve the transmission distance, efficiency and power is one of the important research directions of WPT, is also the premise of small power equipment to realize wireless charging.


30

( )( )( / 1)

ohm rad ohm rad L

m r

R R R R Rf dK K η

+ + +=

−

By adjusting the resonance frequency on the basis of distance, we can achieve the optimization of system efficiency, can stabilize the impact of distance on transfer efficiency to make the system run efficiently。

With frequency control , transfer efficiency is basically stable

Frequency tuning values vs. distance

Our team put forward a kind of efficiency optimization method based on frequency control

3、 The optimization method of Transfer efficiency


uLT

CTVT1

VT2

Phased inductive circuits designed by our team

电压和电流

(p.

u.)

0

1

-1

θ=0˚

a) The U and I waveform before harmonization control

b) The U and I waveform after harmonization control

研究思路 4、Load matching technology and minimal access technology

Minimal access technology Transmitter and receiver of the magnetic coupling wireless transmission system is a resonance of organic whole, have good mechanical and electrical symmetry. The introduction of high-frequency rectifier device affects the system. Reducing the intervention effect of technology as far as possible is the minimal access technology.


Other Concerns

Electromagnetic environment and electromagnetic compatibility

Standardization and marketing issues


Will WPT bring the problem of electromagnetic radiation or the problem of Electromagnetic compatibility？

Main difficulty： 1、The affecting mechanism of the electromagnetic field on organisms 2、It is not easy for the experiment to prove the degrees of its effect 3、The complexity of the electromagnetic compatibility problem requires a balance

between the following two factors: the system does not produce electromagnetic disturbance to the outside world and the system is immune to the interference from outside world。

The magnetic field intensity distribution of 5kW wireless power transmission system had been tested by The University of Utah ,The results meet the International Committee of the Non-Ionizing Radiation Protection (ICNIRP) in the safety requirements.

1、Electromagnetic environment and electromagnetic compatibility problems


Technology Standardization is essential for the popularization and application of WPT. With the development of WPT and extension of its application， there are three main international WPT technology related technical standards：Qi Standard（Wireless Power Consortium)、A4WP(Alliance for Wireless Power )、CE4A（Consumer Electronics for Automotive）.From 2012，our team are actively involved in the discussion and formulation of IEC international standard electric vehicles wireless charging !

2、 Standardization and marketing issues


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High-power high-frequency power supply

High-power mid-range wireless transmission equipment

High-power high-frequency regulated rectifier

Electric vehicle battery management system

Intelligent vehicle terminal

Advanced application platform

wireless charging –Major Facilities

Relevant major

Facilities

The wireless power transmission technology research group in Southeast University has been dedicated to the research of high frequency power supply over years and has formed different power supply design schemes based on inverter, resonant and micro signal power amplifying technology and has developed a series of experimental prototypes.

A power supply with 4 kW max power developed by Huang’s research group

A 3 kW power supply developed by Huang’s research group

High-power high-frequency power supply

wireless charging –Major facilities

High-power mid-range wireless transmission equipment ! The wireless transmission device is the core equipment accomplishing wireless

transmission of energy, of which performance will directly determine the quality of wireless energy transmission.

The high-power mid-range transmission equipment platform developed by Huang’s research group can complete different researches on transmission characteristics under a variety of

situations .

wireless charging –Major equipment

High-power high-frequency regulated rectifier ! The high-power high-frequency regulated rectifier is a device collecting and

converting wireless energy, which is mainly used to solve the stability problem of the system frequency, the regulation of output power and cooling problems in the process of electric vehicle charging. According to the load characteristics of electric vehicle, it can realize the minimum access technology with the transmission system.

A 2-3KW high-frequency regulated rectifier developed by Huang’s research group can realize stable output voltage under a high-power high-frequency environment.


Smart vehicle terminal ! The smart vehicle terminal is used to collect information including

GPS signals and the vehicle state .It can upload the information such as position, speed, direction, time and the alarm signal, the vehicle state and management information to the center through the communication system. In the meantime, it can receive a variety of scheduling and control commands issued by the center. It’s the key equipment for the electric vehicle to realize smart control 。

The smart vehicle terminal developed by Huang’s research group can check the vehicle status, location and exchange information with the scheduling platform.


Advanced Application Platform ! According to GPS signals, Smart Vehicle Terminal can monitor

electrical vehicle charging and discharging conditions in a region, and further improve the intelligent management of vehicles and dispatching.

The research group developed the smart deployment of electric vehicle platform for interactive dispatching, which can achieve dispatching and simulation analysis for 5000 electric vehicles .


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Currently, the research group undertakes a number of national projects, laying the foundation of wireless charging demonstration platform

(1) Exploration of resonant coupling wireless power transmission theory and

the application of its electric vehicle wireless charging technology (2) Applied research of non-radiative electromagnetic resonant tunneling in

high-power electric vehicle wireless charging technology (3) The key technology of electric vehicle wireless charging (4) The wireless power transmission technology (5) Research on technology based on wireless charging and discharging of

electric vehicles and smart grid interactive technology (6) Magnetically coupled resonant electromagnetic environment of wireless

energy transmission ……

Demonstration platform of Southeast University

[1] Research on Power Frequency Electromagnetic Environment of UHVAC Wires and Related Electrostatic Induction Effect [2] Achieving maximum power transfer of inductively coupled wireless power transfer system based on dynamic tuning control [3] Transfer efficiency optimal control of magnetic resonance coupled system of wireless power transfer based on frequency control [4]基于动态调谐实现感应耦合无线电能传输系统的最大功率传输，中国科学:技术科学 [5]基于频率控制的磁耦合共振式无线电力传输系统传输效率优化控制，中国科学:技术科学 [6]基于PZT的超声波无接触能量传输系统的研究, 电工技术学报

Currently ,the research group has published more than 40 papers , laying the foundation of wireless charging demonstration platform

Currently, the research group has more than 40 patents about “wireless power transmission technology”

1. Adaptive electric vehicle wireless charging and discharging device and application methods 2.A high frequency power supply system based on wireless transmission device 3. high power transmission methods based on wireless transmission mode 4.Frequency coordination control device of wireless power transmission system 5. Adaptive electric vehicle wireless charging and discharging device ……


Research group are actively involved in domestic and international exchanges in the fields of wireless power transmission

2012, the research group participated in the IEC electric vehicle wireless charging discussion and formulation of international standards, hoping for contributing to the development of the wireless charging of electric vehicles August 2012, the first time that wireless power transmission technology was listed as thematic elements in international conference, invited to attend PIERS 2012 Moscow conference. This is the wireless power transmission technology as a discussion topic for the first time a wide range of cross-border exchanges.

April 2013, participated in international wireless conference organized by IEEE IWS2013, was invited as a guest to report wireless power transmission technology, Beijing

October 2011, participated in the 57 Special Academic Salon held by China Science and Technology Association, its theme is "wireless power transmission technology“, Tianjin

November 2012 , Wireless Power Summit 2012，Dallas

November 2012, wireless power transmission technology seminar, Chongqing

May 2013, As a co-organizer, participated in the China Electrotechnical Society "organized by the wireless power transmission and application of key technologies Symposium (International)", Guiyang.


Research group has already possessed system integration technology, and is setting up wireless charging for EVs, EVs and the grid interactive demonstration platform.

Developed by our team ：The first set of

magnetic resonance wireless charging system for

electric cars, the first domestic vehicle wireless

charging of pure electric vehicles.


We integrated the car network technology, the wireless power transmission technology with smart grid technologies, to build a demonstration platform for wireless charging electric vehicles, electric vehicles and electric vehicles, interaction between electric vehicles and the grid.

Car networking technology use the car as a node, via wireless communication devices to obtain the information to connect to the platform to manage the network. Wireless charging / power supply technology is based on the vehicle for energy nodes, v i a r a d i o t r a n s m i s s i o n technology and other means to be able to connect to the grid.


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The overall layout of demonstration platform Power system dynamic

simulation experiment system wireless charging

Experimental system for EVs

+


The technical scheme of demonstration platform


Wind Power

Analog Devices

Solar Power

Analog Devices

Generator Load Simulator

Simulation grid scheduling

system

Wired charging terminals

EV（3KW）

wire

wire wire

Wireless charging terminal

EV（3KW）

wireless

grid

Experimental platform for wireless charging of EV

Power system dynamic simulation experiment

platform

Energy flow

Information flow

communication

2KW 1KW 2*5KW 3KW

hardware solutions


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Summary and Outlook

u Wireless charging represents the general trend in the future。

u Electromagnetic resonant can well meet the demands of the EV wireless charging

for power, distance, efficiency, and electromagnetic radiation 。

u Magnetic resonance wireless charging technology needs to address the core

technology ，Including: the effectiveness of the system with different topologies,

the system transmission efficiency optimization method, high-frequency power and

rectification, load matching technology and the minimum access technology. u  Wireless charging system for electric vehicles should have the following major

facilities, including ：High frequency power, high-power medium-range wireless

transmission equipment, high-power high-frequency rectifier regulator, electric

vehicle battery management systems, intelligent vehicle terminal

u  With regard to the interaction between smart grid and electric vehicle, electric car

wireless charging demonstration platform is well developed

Our group is willing to cooperate and collaborate with colleagues

home and abroad, contribute to the development of EVs and

construction of smart grid

Warmest invitation: October 2014, the f i r s t n a t i o n a l w i r e l e s s p o w e r transmission technology International Conference will be hosted by Southeast University, Nanjing.

Summary and Outlook

Dr. Huang Xueliang Professor, Dean of School of EE Southeast University No.2 Sipailou , Nanjing 210096 Jiang Su Province , China Mobile :(86)13770520753

E-mail：[email protected]

Thank you！

Wireless Charging Technology of Electric Vehicle

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