Making the Case for Dynamic Wireless Charging

Srdjan LukicNorth Carolina State University

Suite 100, Keystone Science Center1791 Varsity DriveRaleigh, NC 27606

Challenges to Li-ion Battery Based Transportation Systems

• Energy density (200Wh/kg versus 12,000Wh/kg for petroleum); 

• High initial cost of the batteries (up to  $1000/kWh with a long term goal of $300/kWh) 

• Charge rate limitations due to the electrochemical processes in the battery 

• Battery degradation limits the acceptance of battery powered vehicles due to hard‐to‐predict component life 

• Environmental costs associated with producing and disposing of electrochemical batteries. 

Extending Vehicle Range Through Hybridization

• Hybridization can improve vehicle range– ICE‐Battery Hybrid: 

• Chevy Volt 38 miles on 16.5kWh pack; 380 mile range

– Grid‐Battery Hybrid• Goal: Design Vehicle to cover 300 mile range

UDDS HWFET HW_MTN

Insight (8kWh) 38.17 37.14 22.99

Impala (11kWh) 30.97 34.83 15.71

Explorer (15kWh) 36.09 33.00 18.83

Driving Range for Pure EV in miles

Infrastructure Requirements for Extending Vehicle Range to 300 Miles

Z. Pantic, S. Bai; S.M. Lukic, "Inductively coupled power transfer for continuously powered electric vehicles," Vehicle Power and Propulsion Conference, pp.1271-1278, 7-10 Sept. 2009

Optimization Results (PWPT=30kW, =1)

UDDS HWFET HW_MTN

UDDS

LWPT (m) 55.4 109 120.7

Cover.% 0.46% 0.91% 1%

HWFET

LWPT (m) 2,804 4,501 7,234

Cover.% 17% 27.3% 43.8%

HW_MTN

LWPT (m) 24,014 49,241 89,566

Cover.% 17.2% 35.4% 64.3%

Are Grid-Battery Hybrids Efficient

Source: www.fueleconomy.gov/feg/atv.shtml

WPT/Grid Losses10‐20%

Electric Machine/Storage Losses10%

Conventional Vehicle Power Flow

System Design Challenges

• Reduce the Losses in the Power Electronics• Reduce Losses in Magnetic Link (Determined by the Coupling

and the loaded Quality factors of the coils)• System Tuning to Maintain Resonance

Z. Pantic, K. Lee and S. Lukic, “Multi‐resonant systems for Inductive Power Transfer” (Provisional Patent filed: February 2013) 

K. Lee, Z. Pantic, S.M. Lukic, “Reciever‐position‐controlled field focusing for dynamic inductive power transfer systems” (Provisional Patent Filed February 2013)

Z. Pantic and S. Lukic, "Framework and topology for active tuning of parallel compensated receivers in wireless power transfer systems," Power Electronics, IEEE Transactions on, vol. PP, no. 99, pp. 1‐1 2012.Z. Pantic, S. Bai and S.M. Lukic “A new tri‐state‐boost‐based pickup topology for inductive power transfer applications” presented at the IEEE Energy Conversion Congress and Exposition (ECCE), Phoenix, AZ, September 2011

Z. Pantic, S. Bai, S.M. Lukic, "ZCS LCC‐Compensated Resonant Inverter for Inductive‐Power‐Transfer Application," IEEE Transactions on Industrial Electronics, vol.58, no.8, pp.3500‐3510, Aug. 2011

Z. Pantic, B. Heacock and S. M. Lukic “Magnetic Link Optimization for Wireless Power Transfer Applications: Modeling and Experimental Validation for Resonant Tubular Copper Coils” IEEE Energy Conversion Congress and Exposition (ECCE), Raleigh, NC, September 2012,Z. Pantic and S. Lukic, “Computationally‐Efficient, Generalized Expressions for the Proximity‐Effect in Multi‐Layer, Multi‐Turn Tubular Coils for Wireless Power Transfer Systems”, submitted to IEEE Transactions on Magnetics in October 2012. 

WPT – Research Overview

7

Contribution 4: New design of a LCC compensation circuit that  significantly reduces inverter switching losses

Contribution 3: Modeling of a multi‐turn,multi‐layer hollow‐tube coil

Contribution 1: Tri‐state‐boost‐based system for active tuning of a parallel compensated pick‐up that enables multi‐receiver systems

Contribution 5: Reciever‐position‐controlled field focusing for dynamic inductive power transfer systems

Contribution 2: Multi‐resonant Wireless Inductive Power Transfer

Multi Resonant Power Transfer

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Final Thoughts

• Dynamic Wireless Charging Can Effectively Compete with other hybridization methods in terms of efficiency

• Infrastructure requirements for powering moving vehicles is very low in urban areas (1%) and moderate to high on high-speed roads(20-30%)

• Infrastructure utilization could be substantially higher for dynamic charging infrastructure compared to conductive charging

Thanks!