Wireless Power Transfer for Light-Duty Plug-in/Electric Vehicles and Alignment Methodology

Abstract

The Recommended Practice 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. The specification defines various charging levels that are based on the levels defined for SAE J1772 conductive AC charge levels 1, 2, and 3, with some variations. A standard for wireless power transfer (WPT) based on these charge levels 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.In the near term, vehicles that are able to be charged wirelessly under Recommended Practice SAE J2954 should also be able to be charged by SAE J1772 plug-in chargers.This Recommended Practice is planned to be standardized after the 2018 timeframe after receiving vehicle data. The contents, including frequency, parameters, specifications, procedures, and other contents of this Recommended Practice, are to be re-evaluated at that time to allow for additional developments and future innovations.SAE Recommended Practice SAE J2954 addresses unidirectional charging, from grid to vehicle; bidirectional energy transfer may be evaluated for a future standard. This Recommended Practice 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 Recommended Practice J2954 is meant to be used for interoperability, performance and emissions testing, where a single standard coil-set has been chosen for the WPT power class 1, 2 and 3, up to 11 kW 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 Recommended Practices is to be demonstrated.The future standard, will use this performance based SAE J2954 standard Test Station to establish a uniform way to demonstrate design for both the electrified vehicle (VA) and WEVSE (GA) components safety, interoperability, performance, and EM emissions through testing. 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.