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United States Regulations for Wireless Power Transfer

Wireless power transfer devices introduced on the United States market are regulated by the Federal Communications Commission (FCC). Depending on the intended function of the device and the communication capabilities present, a wireless power transfer system may be evaluated under either FCC Part 15 or FCC Part 18.

At a glance

The FCC distinguishes between wireless power transfer systems operating as intentional radiators and systems classified as Industrial, Scientific and Medical (ISM) equipment.

Regulatory Framework

The Federal Communications Commission (FCC) is responsible for regulating wireless power transfer equipment in the United States. Depending on the characteristics of the system, a WPT device can generally enter the market through two regulatory pathways: FCC Part 15 or FCC Part 18.

An important aspect of the FCC framework is that composite devices may be evaluated separately for their different functionalities. For example, a wireless charger that also contains a communication module can have its charging functionality and communication functionality assessed independently.

The choice between Part 15 and Part 18 has significant implications for operating frequencies, certification requirements, permitted field strengths and market access procedures.

FCC Part 15

FCC Part 15 regulates devices classified as intentional radiators. Because wireless power transfer systems intentionally generate electromagnetic fields to transfer energy, they can fall within this category.

Part 15 devices are permitted to operate only within predefined frequency bands and must satisfy corresponding emission limits. These limits are intended to minimize interference with licensed radio services and other spectrum users.

Certain frequency ranges are prohibited or heavily restricted. Consequently, some wireless power transfer operating frequencies may require special care during the design stage to ensure compliance with FCC spectrum regulations.

A key characteristic of Part 15 devices is that certification is generally required before the product can be marketed. Compliance is assessed through testing and review by an authorized Telecommunication Certification Body (TCB).

Key Characteristics

Aspect FCC Part 15
Classification Intentional Radiator
Operating Frequencies Specific permitted frequency bands
Certification Required through a TCB
Main Focus Spectrum protection and interference control

FCC Part 18

FCC Part 18 regulates Industrial, Scientific and Medical (ISM) equipment. Although these devices are generally intended for non-communication applications, certain wireless power transfer systems may also be evaluated under this framework.

Wireless power transfer devices whose communication functionality is exclusively used for power control purposes may qualify for regulation under Part 18. This pathway can be attractive because it often allows operation with higher permitted field strengths in designated ISM frequency bands.

Another important advantage is that certification through a Telecommunication Certification Body is not always required. Instead, manufacturers may demonstrate compliance using a Supplier's Declaration of Conformity procedure.

The increased flexibility offered by Part 18 comes with potential drawbacks. Devices operating in crowded RF environments may experience or generate interference because higher emission levels are permitted than under certain Part 15 configurations.

Part 18 therefore establishes exposure and emission limits for each applicable ISM frequency band that wireless power transfer equipment must satisfy.

Key Characteristics

Aspect FCC Part 18
Classification Industrial, Scientific and Medical equipment
Communication Function Only power-control communication permitted
Certification May be replaced by Supplier's Declaration of Conformity
Main Advantage Higher allowable emission levels in ISM bands

RF Exposure Compliance

Both Part 15 and Part 18 require compliance with RF exposure limits. These limits are intended to ensure safe operation of wireless power transfer systems for users and nearby individuals.

RF exposure compliance is evaluated using standardized measurement and assessment procedures. Depending on the operating frequency, power level and application, the evaluation may include measurements of electric and magnetic field strength as well as computational safety analyses.

Dedicated FCC guidance documents and industry standards provide the methodologies needed to perform these assessments consistently and demonstrate compliance.

Common Reference Documents

Document Purpose
IEEE Std C63.30 Measurement procedures for wireless power transfer systems
FCC KDB 680103 Guidance for RF exposure evaluation

Comparison of FCC Pathways

The table below summarizes the two principal FCC regulatory pathways applicable to wireless power transfer systems in the United States.

Requirement FCC Part 15 FCC Part 18
Device Type Intentional Radiator ISM Equipment
Communication Allowed Yes Only for power control
Certification Required May use Supplier's Declaration of Conformity
Emission Limits Generally more restrictive Higher limits in specific ISM bands
Main Advantage Broad applicability Simplified compliance pathway and higher power capability

Sources

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