Recommended Practice, SAE J2954™ published in 2017 is the most comprehensive standardization for Wireless Power Transfer for both plug-in hybrid & battery electric light duty vehicles. In order to ensure interoperability, SAE J2954 established a common 85kHz frequency band over the three power classes WPT1-3 (3.7kW and 11kW). Each WPT Power Class has specific coils defined to give a baseline for magnetic coupling.
The document gives guidance for design the minimum safety, interoperability and EMC & EMF for this technology for charging wirelessly between a Ground Assembly and Vehicle up to 11kW (WPT3). Coupled with communications and LPE (Low Power Excitation), SAE J2954 has established a minimum specification towards automated parking and charging for conventional and autonomous vehicles.
SAE J2954 provides a Standard Test Stand up to 7.7kW (WPT2) which enables bench safety and performance confirmation of designs for development and a means for ground assembly validation without the need of a vehicle assembly to be provided. Updates in 2018 will include a test stand specification up to WPT3. The SAE J2954 test stand has bench test validated systems from WPT1-WPT3 and is planning vehicle testing in 2018 to establish data to be used to complete the upcoming standard in 2019. Average efficiency over all testing has been 90% andwith alignment even higher.
The SAE J2954/2 Technical Information Report, planned for late 2018 will be providing the first ever guideline for development of high power WPT up to 500kW (WPT9) for Heavy Duty Electric Vehicles.