The Society of Automotive Engineers International (SAE) has approved the publication of its first wireless charging guidelines for electric vehicles (EVs), which pave the way toward an industry-wide wireless charging standard for all makes of automobiles.
Available from May 31, ‘SAE TIR J2954 Wireless Power Transfer for Light-Duty Plug-In/Electric Vehicles and Alignment Methodology’ is a milestone industry guideline to establish wireless power transfer between infrastructure, vehicle suppliers and OEMs for plug-in electric and battery electric vehicles (PEV/BEV). With wireless charging quickly becoming mainstream for consumer electronic devices in low-power applications, standardization is needed for commercialization of high-power wireless power transfer (WPT) of EVs. In order to achieve a basis for the start of commercialization for WPT, it is important to define criteria for safety and electromagnetic limits, efficiency and interoperability targets, as well as a test setup for the acceptance of WPT; all of which is addressed in the J2954 guidelines.
The SAE’s current J1772 standard has created an industry-wide protocol for plug-in charging that has been adopted by the majority of auto makers. The TIR J2954 wireless guidelines have been signed by the bulk of current EV makers, together with several electric bus manufacturers, Tier 1 OEMs and charging technology suppliers. SAE TIR J2954 establishes a common frequency band using 85kHz (81.39 – 90kHz) for all light-duty vehicle systems. In addition, four classes of WPT levels are given, with the proviso that future revisions may include even higher power levels. Two levels are currently specified, 3.7kW (WPT 1) and 7.7kW (WPT 2), with 11kW (WPT 3) and 22kW (WPT 4) to be specified in a future revision of J2954. WPT 1-2 compatible systems have been built by auto makers and suppliers and are currently under test in the USA with a cross-industry team, including the US Department of Energy (DOE), and the Idaho and Argonne National Labs. The test data, first on the bench, and later in the vehicle, will be used to finalize the Standard by 2018, in order to support the roll-out of the technology.
TIR J2954 is the first step in standardization, and was developed by SAE International’s EV Wireless Power Transfer committee, established in 2010. Jesse Schneider serves as the chair of the committee and is also the fuel cell, electric vehicle and standards development manager at BMW North America. He presented the SAE TIR J2954 last week during the Conference on Electric Roads & Vehicles (CERV) in Logan, Utah.
“Wireless power transfer, using SAE TIR J2954, is a game-changer for EVs. This first in a series of documents will enable consumers to simply park their vehicles into spaces equipped with TIR J2954 equipment and walk away without doing anything to charge their EV,” explained Schneider. “Standardization of both the vehicle and ground infrastructure WPT has started with SAE TIR J2954. The frequency band, safety, interoperability, EMC/ EMF limits, as well as coil definitions from SAE TIR J2954, enable any compatible vehicle to charge wirelessly from its WPT home charger, work, or a shopping mall WPT charger, with the same charging ability. All of this makes it possible to seamlessly transfer power over an air gap with high efficiencies. SAE TIR J2954 WPT automates the process for charging and extends the range for the vehicle customer, only by parking in the right spot.”