Xiaodong Shi (Lead Editor-WPT Series)
My name is Xiaodong Shi and I am the lead editor for IEEE’s Transportation Electrification Initiative eNewsletter Special edition on Wireless Power Transfer (WPT). It has been a pleasure to have brought you this important two-part series on an important emerging technology that could enable the widespread adoption of electric vehicles. In part one of the series (the July edition), we covered the basics concepts and recent developments in research and WPT education methods. In this, our concluding part of the series, (September edition) we will look at the commercialization of WPT, Roadway powered vehicles, WPT thermal modeling and WPT safety concerns.
by Matt Jurjevich
An Introduction to Inductive Charging
There is a new charging technology making its way on to our streets or, should I say into our streets. It’s called Wireless Inductive Power Transfer (WIPT) or just “Inductive Charging”, and it’s poised to change the way we supply power to our electric vehicles forever. The focus of this article is to provide an overview of how WIPT is already working to revolutionize Bus Rapid Transportation Systems across the world, and assist in the inevitable transition to electrified public transportation systems.
Chun T. Rim, Senior Member, IEEE (firstname.lastname@example.org)
Recent developments of electric vehicle technologies have largely been driven by requirements to reduce emissions of greenhouse gases (GHG) such as CO2 and to mitigate air pollution especially in urban areas. Various electric vehicles use batteries for energy storage therefore heavily reply on the available battery products and their technology development. Hybrid electric vehicles (HEV) are also gaining popularity due to the limited use of the battery for short term energy recovery.
In contrast, roadway powered electric vehicles (RPEV) among other electric vehicles do not necessarily require battery energy storage for their traction as they are using dynamic wireless power transfer systems (WPTS) to get the power as they are moving on roads. This is seen as a promising candidate for future propulsion of small cars, taxies, buses, trams, trucks and trains. It can even be competitive with internal combustion engine powered vehicles.
Joe Bablo, Ken Boyce, and Hai Jiang
Underwriters Laboratories (UL)
The development of wireless charging systems for electric vehicles has been in process for some time. This technology offers the user a “hands free” method of charging, but also brings along some safety aspects that are unique to wireless charging.
Standardization efforts around design and safety are in process, and these standards will be needed to insure safe equipment that is functional and able to operate as intended when used in various combinations of charge station and vehicle (interoperability).
This paper will focus on the unique aspects of wireless charging as they relate to safety and potential safety certification of the off board Electric Vehicle Supply Equipment (EVSE), how these issues are different when compare to conductive charging, and how those differences affect the way certification can be handled.
By Xiao Hu
Co Written and edited by Manoj Kumar Mallela and Paul Paret, editors of IEEE TEI Newsletter
This article is written based on the part of presentation given by Dr. Xiao Hu at the Wireless Power Transfer (WPT) workshop at The University of Michigan in Dearborn, MI, March 13 2014. Dr. Xiao Hu is the principal engineer at ANSYS Inc.
The wireless transformer used in high-power, wireless power transfer is mainly an electromagnetic device and temperature performance is key to its efficiency. Temperature has a strong impact on efficiency of such a device since electromagnetic properties, e.g. conductivity and permeability, are temperature dependent. An increase of temperature can increase conductivity and thus generate more heat dissipation and cause a decrease of overall efficiency. As for the core material used in such devices, tests show that some materials could completely lose magnetic characteristics when temperatures exceed 200 0C and very high temperatures pose safety concerns. Finally, where thermal stressing is a concern, then one must know the temperature ranges before thermal stress calculations can be performed. Therefore, when doing accurate simulations for wireless power transform, coupled electromagnetic and thermal analysis is necessary.