Page 7 - PEN Ebook March 2021

COVER STORY - DESIGN Cover Story - Design

Wireless charging poses significant challenges to HOW WIRELESS CHARGING

designers. The efficiency of the wireless power WORKS
transfer depends on the design of the magnetics Wireless charging uses an alternating magnetic
(coils) and the electronics. It also requires a deep field to transfer energy from a transmitter coil to
level of system knowledge and expertise when a receiver coil. The energy transfer's effective-
balancing different system parameters, from coil ness between coils is referred to as "coupling"
inductance over voltage and current levels to and depends on multiple parameters, including
mechanical packaging and electromagnetic inter- mechanical design of the coil, spacing, and align-
ference (EMI). In addition, metallic foreign ob- ment. On the transmitter side, a MOSFET-based
jects (e.g. keys and coins) can be a safety hazard inverter converts the DC power that goes into the

during charging and must be reliably detected wireless power transmitter into an AC waveform
through a process called foreign object detec- to drive the coil and create an alternating mag-
tion (FOD). But with optimized components and netic field. A wireless power controller measures
great attention to magnetics, electronics, and the and control voltages and currents in the coil in
end-application, a high-efficiency wireless power real-time and enables communication to the re-
system can be achieved, coming close to wired ceiver. In order to guarantee safe wireless power
charging efficiency levels. transfer, a hardware authentication IC such as

the OPTIGA™ Trust Charge SLS32AIA can be
Wireless charging used to authenticate the transmitter to the re-

ceiver. Some transmitter designs use several coils
systems in higher

power applications-

Considerations, challenges,

and solutions

By Marcel Konstantinov, Technical Marketing Manager Wireless Power at Infineon
Technologies and Ken Moore, CEO at Spark Connected

Various benefits drive the market for wireless the 2019 – 2025 period, reaching 27 billion USD
charging: ease-of-use and no hassling with in 2025. More and more applications are applying
cables provide a high level of convenience and wireless charging to make use of these bene-
excellent user experience; No-port opening ena- fits (Figure 1). Infineon, partnering with Spark
bles aesthetic designs and sealing for operation Connected, offers complete solutions for wireless
in harsh environments; Standardization enables charging with dedicated wireless power controllers,
interoperability across brands and flexibility. including software IP, MOSFETs, drivers, security ICs
Logically, the wireless charging market is grow- and application-optimized reference designs.
ing strongly with a CAGR of about 30 percent in Figure 1: More and more wireless charging applications offer convenience and flexibility to the users.

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