CAREER: High-Frequency Power Electronics for Wireless Power Transfer Systems

Cornell University, Ithaca NY

Investigators

Abstract

Wireless power transfer (WPT) has the potential to address critical energy issues and improve human quality of life by enabling autonomous charging in applications ranging from electric vehicles (EVs) and robotics to portable electronics and biomedical implants. For example, efficient, small, cost-effective, and safe WPT can drastically reduce the need for expensive and bulky on-board batteries, extend range, and accelerate EV penetration. With road transportation accounting for 22% of the nation's total energy consumption, and EVs having roughly twice the well-to-wheel efficiency of gasoline vehicles, even a 10% EV penetration (versus 0.1% currently) can reduce total U.S. energy consumption by over 1%. Likewise, effective WPT can enable artificial heart pumps without abdominal-wall-penetrating electric cords, avoiding discomfort and potential infections for the 5.1 million people in the U.S. suffering from heart failure. Furthermore, WPT could eliminate the need for cardiac pacemaker battery replacement surgeries for nearly 40,000 people each year. However, for WPT systems to be widely adopted, considerable improvements are needed in their performance, cost, and safety. This integrated research and education career development proposal aims to make fundamental advancements in high frequency (1-100 MHz) power electronics technologies, and leverage exciting WPT applications to ignite the imagination of future engineers. The program's broader educational goals include the training of graduate research students and undergraduates participating through the University of Colorado's (CU) Discovery Learning Apprenticeship Program. Incorporating the research findings into the CU Boulder curriculum and disseminating the findings more broadly through a free online course will enhance the education of students at CU Boulder, community colleges, and elsewhere. The special outreach program for K-12 students, involving them in the development of educational videos, will expose them to the role of power electronics and WPT in improving energy efficiency and quality of life and attract them to pursue STEM careers. To achieve the goal of WPT systems with efficiencies, sizes, and safety comparable to their wired counterparts, the research objectives of this CAREER proposal are to: (i) generalize the new step-superposition (S2) analysis technique introduced by the PI, and use it to better model and optimize high-order resonant converters with multiple inverters and/or rectifiers; (ii) innovate and employ high-order resonant converter topologies with appropriately controlled multiple inverters and rectifiers in inductive and capacitive WPT systems to compensate for changes in coupling and achieve higher efficiency and reduced size, then validate these advantages through a series of experimental prototypes; and (iii) demonstrate feasibility of near-field focusing and enhanced safety through distributed WPT architectures by measuring the reduction in fringing fields in prototypes with different coupler geometries and configurations. This effort enables important innovations and fundamental advances. The step-superposition analysis technique developed here will enable accurate modeling and optimization of high-order resonant converters for WPT applications, as well as other power electronic and complex system applications. Having demonstrated high-order multi-inverter/rectifier resonant converters to provide efficiency benefits in grid-interfaced power electronics, the PI's research will introduce advanced variants that effectively compensate for variations in coupling in WPT systems, while operating at fixed frequency within ISM (i.e., industrial, scientific and medical) frequency bands. The research will also yield a better understanding of near-field phased-array field focusing through distributed couplers designed for field cancellation, and enable dramatic advances in power transfer densities and safety.