A New Design Approach to Mitigating the Effect of Parasitics in Capacitive Wireless Power Transfer Systems for Electric Vehicle Charging

Journal Article · Mon Jul 29 00:00:00 EDT 2019 · IEEE Transactions on Transportation Electrification (Online)

DOI:https://doi.org/10.1109/tte.2019.2931869· OSTI ID:1799044

Sinha, Sreyam  ^[1]; Kumar, Ashish  ^[2]; Regensburger, Brandon  ^[1]; Afridi, Khurram K.  ^[1]

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1. Cornell Univ., Ithaca, NY (United States)
2. Texas Instruments, Santa Clara, CA (United States)

This paper introduces a new design approach to mitigate the effect of parasitic capacitances and achieve high performance in large air-gap capacitive wireless power transfer (WPT) systems for electric vehicle (EV) charging. In a capacitive WPT system for EVs, the vehicle chassis and roadway introduce multiple parasitic capacitances that can overwhelm the coupling capacitance and severely degrade power transfer and efficiency. The proposed approach addresses this challenge by employing split-inductor matching networks, which allow the complex network of parasitic capacitances to be simplified into an equivalent four-capacitance model. The shunt capacitances of this model are directly utilized as the matching network capacitors, hence, absorbing the parasitic capacitances and eliminating the need for discrete high-voltage capacitors. A systematic procedure is developed to accurately measure the equivalent capacitances of the model, enabling the system's performance to be reliably predicted. The proposed approach is used to design two 6.78-MHz 12-cm air-gap prototype capacitive WPT systems with capacitor-free matching networks. The first system transfers up to 590 W using 150-cm ² square coupling plates and achieves an efficiency of 88.4%. The second prototype system transfers up to 1217 W using 118-cm ² circular coupling plates, achieving a power transfer density of 51.6 kW/m ² . The measured output power profiles of the two systems match well with their predicted counterparts, validating the proposed design approach.

• Research Organization: Univ. of Colorado, Boulder, CO (United States)
• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• Grant/Contract Number: AR0000618
• OSTI ID: 1799044
• Journal Information: IEEE Transactions on Transportation Electrification (Online), Vol. 5, Issue 4; ISSN 2332-7782
• Publisher: IEEE
• Country of Publication: United States
• Language: English

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