Wireless Power Transfer for Light-Duty Plug-in/Electric Vehicles and Alignment Methodology
The Standard SAE J2954 establishes an industry-wide specification that defines acceptable criteria for interoperability, electromagnetic compatibility, EMF, minimum performance, safety, and testing for wireless charging of light-duty electric and plug-in electric vehicles. A standard for wireless power transfer (WPT) based on the charge levels from WPT 1-3 (3.7-11 kW) enables selection of a charging rate based on vehicle requirements, thus allowing for better vehicle packaging and ease of customer use. The specification supports home (private) charging and public wireless charging.
The SAE Standard J2954 addresses unidirectional charging, from grid to vehicle; bidirectional energy transfer may be evaluated for a future standard. This Standard is intended to be used in stationary applications (charging while vehicle is not in motion); dynamic applications may be considered in the future. In this version only above-ground (surface mounted) installations are covered; flush mounted installations have been discussed but are not yet ready for inclusion.
SAE Standard J2954 is meant to be used for interoperability, performance and emissions testing, where a single standard coil-set has been chosen per Z-classes (1 through 3) using circular topology. This SAE J2954 Test Station is meant to provide a baseline where compatibility with the content of the Standards is to be demonstrated.
This document uses this performance based SAE J2954 standard Test Station to establish a uniform way to demonstrate design for both the electrified vehicle assembly (VA) and WEVSE ground assembly (GA) components related to safety, interoperability, performance, and EM emissions. The goal is to have a common methodology to validate WPT and alignment, production designs between different power classes, and topologies for both the vehicle and infrastructure.
Rationale: Electrified powertrains, specifically battery electric and plug-in electric (BEV/PHEV) vehicles are projected internationally to become more prevalent in production due to environmental factors (such as CO2 emissions), regulations (such as the Greenhouse Gas and the California ZEV Mandate), and the increasing price of fossil fuels. The main benefits of electrified powertrains are eliminating or significantly reducing local emissions while increasing the overall well-to-wheels efficiency. In addition, autonomous vehicles are soon to be more commonplace to allow more convenient and safer transportation, especially in traffic settings and long-distance driving.
Standardized Wireless Power Transfer (WPT, so-called, wireless charging) allows the BEV/PHEV customer an automated and more convenient alternative to plug-in (conductive) charging. Essentially, the customer simply needs to park into a SAE J2954 compatible parking space in order to charge the vehicle. WPT offers the additional advantage to autonomous vehicles enabling autonomous parking with alignment assistance and automated charging (in all weather conditions, such as rain or snow).
It is essential that data-based standards are used as a basis for commercialization of this technology. The SAE J2954 TF has documented the lessons learned from the first stage of testing with real OEM systems in accompanying SAE technical data reports (see references). The SAE J2954 Standard is meant to harmonize with ISO/IEC SDOs in order to make a world-wide WPT standard, first to 11kW. This document will be an evolution of the Recommended Practice J2954 based on interoperability data.