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ARRL Says Manufacturers’ Wireless Power Transfer for Electric Vehicles Petition is Premature


ARRL is opposing a Petition for Rulemaking (RM-11815) by several vehicle manufacturers that calls on the FCC to “adopt field strength limits in Section 18.305 that will allow higher power wireless charging technologies operating in the 79 – 90 kHz range” to accommodate what the petitioners call “next-generation” wireless power transfer for electric vehicles (WPT-EV). Comments filed on October 29 by ARRL contend that the petition is “woefully incomplete and inadequate” in its analysis of consequent out-of-band emissions from WPT-EV systems in the low- and medium-frequency ranges using upward of 11 kW of power. Given the high power levels, ARRL said harmonic emissions from WPT-EV systems could be appreciable, with the AM Broadcast Band and Amateur Radio as potential interference victims. “Interference potential from intentional radiators requires substantial evaluation,” ARRL asserted in its remarks.

The issue of WPT-EV is a World Radiocommunication Conference 2019 (WRC-19) agenda item, for which studies are still under way. The Petition “quite obviously prejudges the outcome of WRC-19 Agenda Item 9.1.6,” ARRL said, stressing that the Petition is simply premature at this point.

“The Petition is typical [of those that] tout a new application of old technology,” ARRL commented. “So as to establish a sense of urgency, the bulk of the Petition is dedicated to establishing a public interest justification for making a rule change now, in order to accommodate the technology.”

The Petition seeks a specific field strength limit of 74.4 dBµA/meter (at a distance of 10 meters), regardless of the charging system’s operating environment. That works out to about 2.07 V per meter (at 10 meters) or 126 dBµV — 126 dB above 1 µV. The Petition presumes that the optimum internationally harmonized frequency range for WPT-EV is already known to be 79 – 90 kHz and that the optimum field strength to minimize any impact on radiocommunication services has been established, ARRL commented.

“The problem, however, is that there is nothing in the four corners of the Petition that would justify those assumptions,” ARRL told the FCC. ARRL pointed out that the International Amateur Radio Union (IARU) expressed concerns about the out-of-band interference potential of WPT-EV in April of 2017.

“Quite obviously, the rollout of WPT-EV has profound implications in terms of its ubiquity in future years,” ARRL said in calling on the Commission to deny the petition without prejudice or dismiss it altogether.

“To make a mistake now in ascertaining the potential for interference to radiocommunications from out-of-band emissions from high-power WPT-EV systems would result in widespread interference, for which there would be no practical, after-the-fact remedy.” ARRL maintained that studies already under way should be permitted to take their course.

“Quite clearly, the petitioners have ‘jumped the gun’ by filing this Petition now,” ARRL concluded.

Filing the Petition jointly were BMW of North America, Ford Motor Company, Nissan of North America, and Toyota of North America, who maintain that “higher power wireless charging will help reduce barriers to consumer acceptance of electric vehicles.” 





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