Further, the SAE International J2954 Task Force for Wireless Power Transfer (WPT) of Light Duty, Electric and Plug-in Electric Vehicles, has agreed upon two key factors for the Technical Information Report (TIR) on interoperability for the first phase of pre-commercial development: a common frequency of operation (85 kHz) and the definition of three power classes for light duty vehicles: WPT 1, 2 and 3. (Earlier post.)

At the recent SAE 2014 Hybrid & Electric Vehicle Technologies Symposium, engineers addressed different aspects of the development of wireless electric vehicle charging (WEVC) in three different presentations.

Paul Guckian from Qualcomm, which is developing the Halo wireless charging technology (3.3 kW, 6.6 kW and 20 kW) emphasized that the main factor for the projected growth of WEVC is its ease of use.

Guckian said that Qualcomm views this as a long-term engagement, with capabilities moving beyond static wireless charging to semi-dynamic (i.e., waiting in traffic, taxi lines, wherever driving is at a slow pace), to fully dynamic charging. Each of these has distinct technology challenges, as well as regulatory challenges.

The key criteria for wireless charging, Guckian said, are:

• Safety
• Coexistence—i.e., not interfering with other wireless systems
• Compliance with worldwide regulations
• Standards compliance
• Efficiency of more than 90%
• Packaging—i.e., volume and weight
• Ease of use—e.g., tolerance to misalignment

The top three regulatory challenges, according to Guckian (who is VP, EMC and Regulatory Engineering at Qualcomm), are:

• Power Transfer Frequency: Meeting regulatory emission limits to prevent harmful interference. SAE has select 85 kHz for WEVC; Qualcomm has worked with Halo implementations at 40, 85 and 145 kHz.

• RF Exposure Compliance: Worldwide existing regulation based on ICNIRP (International Commission on Non-Ionizing Radiation Protection). The use of WEVC raises issues about living object protection (including human factors, detection mechanisms and emergency shutdown time) and foreign object protection—i.e., safety considerations for Induction heating occurring with objects which are made from conductive or ferromagnetic materials.

• Interference to Implantable Devices: Complying with magnetic field immunity limits to prevent upset to implantable medical devices (IMD).

Matt Shirk from the Idaho National Laboratory reported on the testing of the PLUGLESS Level 2 EV Charging System (3.3 kW) by EvatranGroup being done at the lab (as well as testing of DC fast charging and conductive charging).

Perry Jones from Oak Ridge National Laboratory (ORNL) took a longer-range approach, describing analysis being done at the lab on dynamic WEVC. ORNL researcher Zhenghon Lin will present a paper at the upcoming SAE World Congress (2014-01-1965) describing the potential impact on plug-in electric vehicle adoption given dynamic wireless power transfer.

Results show that the impact of DWC varies greatly across consumer segments. Consumers with home charge only are most sensitive to the provision of DWC, while consumers with both home and workplace charging or neither are less so.