Validation of Wireless Power Transfer up to 11kW Based on SAE J2954 with Bench and Vehicle Testing 2019-01-0868

Wireless Power Transfer (WPT) promises automated and highly efficient charging of electric and plug-in-hybrid vehicles. As commercial development proceeds forward, the technical challenges of efficiency, interoperability, interference and safety are a primary focus for this industry.

The SAE Vehicle Wireless Power and Alignment Taskforce published the Recommended Practice J2954 to help harmonize the first phase of high-power WPT technology development. SAE J2954 uses a performance-based approach to standardizing WPT by specifying ground and vehicle assembly coils to be used in a test stand (per Z-class) to validate performance, interoperability and safety. The main goal of this SAE J2954 bench testing campaign was to prove interoperability between WPT systems utilizing different coil magnetic topologies. This type of testing had not been done before on such a scale with real automaker and supplier systems. Several automakers, suppliers and government employees worked together to create a test plan, perform the testing and analyze the results.

To evaluate the interoperability, performance, and electromagnetic emissions of this technology, a bench test program was created, supported by the SAE J2954 WPT and Alignment Taskforce along with the US Department of Energy's Idaho National Lab and TDK North America. The latest tests were conducted between two different power classes (3.7 kW and 11kW) and two different coil magnetic topologies. This report describes the testing program and contains results from the different WPT systems. This testing validates the second stage of SAE J2954 standardization and proves that WPT is not only possible over an air gap with ground clearance of 250mm, but also interoperable across power classes and system designs while achieving high efficiency (many tests were above 90% AC to DC efficiency). In addition, susceptibility of representative medical devices to electromagnetic emissions from WPT systems was assessed. The results of this report are being used as a basis for the future SAE J2954 Standard.