Three EECS power electronics faculty members, Associate Professor Hua “Kevin” Bai, Associate Professor Daniel Costinett, and Chancellor’s Professor Leon Tolbert have a new feature article published in IEEE Power Electronics Magazine, facing to both academia and industry audiences.

“Charging Electric Vehicle Batteries: Wired and Wireless Power Transfer— Exploring EV Charging Technologies,” projects the future trends of EV chargers based on past and present related projects at the University of Tennessee. The authors believe that the EV chargers in the future will exhibit more integration, expedite the charging speed, and provide more grid services.

Key factors for the rapid adoption of electric vehicles (EVs) include the improvement of battery energy density, lifespan and safety, and drastic cost reduction of batteries and power electronics. Power electronics technologies can be found nowadays in many aspects of EVs, altering and transforming the energy from the power source to different forms to feed the loads.

Today, the majority of the on-board chargers and other electronics devices for EVs are separately designed, yielding large sizes and high costs. Both on-board and off-board chargers are mainly unidirectional, lacking the capability to support the grid. During a power grid outage, chargers can only shut down instead of forming a local grid to supply households with power. While extreme fast chargers are emerging, being connected to the local utility grid usually means a higher burden, thereby requiring a major grid upgrade.

In the future, onboard chargers will see more and more integration with other power electronics devices, such as DC-DC converters or DC-AC inverters, yielding more compactness and lower costs. Secondly, the off-board extreme fast charger will begin to connect to transmission lines, which exhibits higher efficiency and lower electrical stress on local utility grids. Lastly, both on-board and off-board chargers will be embedded with more bidirectional features thereby enabling them to provide more grid services, such as frequency modulation, reactive power compensation and universal power supply (UPS).

Additional authors include Ruiyang Qin, Liyan Zhu, Ziwei Liang, Yang Huang, all of the University of Tennessee.

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