unplugging the electric car
TRANSCRIPT
1
Siqi Li, Tommy Nugyen, Weihan Li
Chris Mi, Ph.D, Fellow IEEE
Professor, Department of Electrical and Computer Engineering
Director, DOE GATE Center for Electric Drive Transportation
Unplugging the Electric Car - Wireless charging of electric vehicles with
extremely high efficiency and misalignment
tolerance
Conventional EV Charging 1 2
Fast charging Mostly DC charging in
15 to 30 minutes.
For an EV with a 24kWh
battery pack, charging
in 15 minutes means
96kW. This is way over
the power available in
private homes.
3
Battery swapping Investment of battery
packs; standardization
is difficult; swapping
stations need a lot
investment, space and
manpower; safety and
reliability is of concern
Normal charging AC charging using
level 1 or level 2,voltage at 110V, 220V,6-10 hours per charge
Charge at home or
public space, need
large installation of
charge stations
Wireless Charging
Issues of Con. Charging and
Battery Swapping
Electric safety is of concern:
electric shock due to rain, etc.
Charge station, plug and cable
can be easily damaged, stolen
Charge/swap station takes a lot
of space and affect the views
Methods of WPT
Wireless Power
Transfer
电能的无线传输
Electromagnetic Induction
电磁感应式
Electromagnetic Resonance
电磁谐振式
Radiation
辐射式
Microwave
微波
Laser
激光
Ultrasound
超声波
Radio wave
无线电波
• In 1830’s, Faraday's law of induction
• In 1890’s, Tesla had a dream to send energy wirelessly
• GM EV1 used an Inductive charger in the 1990’s
• 2007, MIT demonstrated a system that can transfer 60W of
power over 2 m distance at very low efficiency
• Wireless/inductive chargers are available on the market
• Qualcomm, Delphi (Witricity), Plugless Power, KAIST, etc.
have developed EV wireless charger prototypes
Wireless market $17 Billion in 2019
Latest Development in Wireless EV Charging
MIT 2007
Tokyo 2009
Intel 2008
Korea KAIST
Leaf 2012
Witricity/Delphi
Japan
India
High cost
Problems and Difficulties • Magnetic field is diminishing proportional to1/r3
• Often the mutual inductance is less than 20% or 10% of the self inductance
• Analytical calculation of coil mutual inductance is next to impossible
• Further analytical method is needed
• Numerical simulation and coupled field - lumped parameter simulation is also of paramount importance
• High frequency HFSS instead of static FEM for high frequency
Large size
Need novel
design Low efficiency
five patent
disclosures
Limited distance
Sensitive to vehicle alignment
The Topology
• Analytical
– Equivalent circuit analysis; S-parameter analysis; Analytical solutions of inductance and capacitances
• Numerical
– Finite element analysis – electromagnetic; High frequency structure simulation - HFSS
– Coupled field and lumped parameter analysis
• Experimental
Exposed field to a human of 1.8-meter high
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
Distance [meter]
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1.60
Ma
g_
B [u
Te
sla
]
Field exposed to a man of 1.8met height
Curve Info
Time='13250ns'
Time='13500ns'
Time='13750ns'
Time='14000ns'
Time='14250ns'
Time='14500ns'
Time='14750ns'
Time='15000ns'
Time='15250ns'
Time='15500ns'
Time='15750ns'
Time='16000ns'
Time='16250ns'
Human’s height [in meter]
Human body is exposed to maximum about 1.6uTesla in foot area
while about 0.06uT in head area.
9
Experimental Verification
Max power: 8kW Max Eff.: 97%
Input voltage
Output current Input current Output voltage
Vehicle Demonstration
• Working closely, we are making a vehicle level demonstration by end of 2013 or early 2014
• We are also working with DENSO to bench mark the design with existing wireless charging systems
• UM is also signing an agreement with Mia Motors, Inc. to commercialize the wireless charging for electric buses.