The goal of this standardization is to ensure interoperability and performance between the wide range of electrified vehicles being developed by carmakers worldwide, and the wireless charging stations that will be widely deployed to streamline the charging of the next generation of EVs and PHEVs. The SAE J2954 Taskforce has been working since 2010 to develop the specifications and standards needed to achieve seamless interoperability.

In December 2016, bench testing for the J2954 taskforce at Idaho National Laboratory demonstrated interoperability between the so-called Double D (DD) and Circular Topologies between 3.7 to 7.7 kW with efficiencies exceeding 85-90% under aligned conditions. (Earlier post.)

WiTricity’s DRIVE series of EV reference designs include 3.7 kW, 7.7 kW and 11 kW, scaling to 22 kW and higher, and is based on the company’s patented magnetic resonance technology. These designs deliver end-to-end efficiency of 91%-94% and combine WiTricity’s Tunable Matching Network (TMN) technology with its circular coil design.

TMN technology allows the wireless charging system to automatically optimize energy transfer between the ground and vehicle in a wide range of real world operating conditions including parking misalignment, differing vehicle ground clearance and varying battery voltage conditions. This flexibility enables wirelessly charged vehicles to interoperate more easily with standards-based charging sources made by different automakers, Tier 1 suppliers and infrastructure suppliers.

WiTricity’s TMN technology is delivered as a compact electronics module embodying proprietary hardware and software algorithms, to be incorporated into both the wireless charging source on the ground and the wireless power capture device on the vehicle.

WiTricity’s DRIVE system is able to maximize efficiency and power delivery over a broad range of parking alignment, battery voltage, and power conditions. In addition, WiTricity’s DRIVE 11 offers direct-to-battery charging to eliminate system losses associated with DC-DC converters and onboard chargers and can be configured to handle a wide range of battery voltage including the latest 800V packs used for next-generation high performance EVs.

Nissan, together with other carmakers, has recognized that interoperability is critical for simplifying the EV charging experience and adoption of EVs more broadly. This means ensuring car owners they can charge their vehicles at any station regardless of vehicle size and type.

Nissan believes in the potential of wireless charging to help advance widespread acceptance of EV motoring. We are very pleased to be working with a technology expert such as WiTricity to advance the state of the art for interoperability, efficiency, and user friendliness.

—Kazuo Yajima, Alliance Global Director of the EV and HEV Engineering Division of Nissan