Wireless Power Transfer from USB

It is desired in some applications to isolate a user from a direct power connection to prevent being shocked, and this requires a wireless power link from a source to a load. A wireless power link also simplifies waterproofing of the receiving device, essential in cases where the device is being used in rhythm with daily functions. In an effort to follow the upcoming standardization of USB cables as the medium for charging cell phones, the power source for linking power to the receiving device should conform for compatibility.

Objective of Design

Our project goal was to design a system that charges a Lithium Polymer battery that is sealed within a portable electronic device from a USB port on a computer, as well as perform fuel gauging on the battery to determine charging status and display the information to the user. The requirements were to achieve at least 20% efficiency of power transfer from USB terminal to the receiving coil on the portable electronic device, provide at least 100mA for charging to the Lithium Polymer, and calculate the battery voltage, charge/discharge current, state of charge, and time-left-to-fully-charged/discharged to finally display these values to the user. As secondary requirements, the coils on the portable device were not to exceed 31x35mm (width x length), and the circuit board 21x40mm (width x length), as well as waterproofing the device and planning to meet IEC 60601-1 and 60601-2 safety and emissions standards.

Project Sponsors


Industry Sponsor: Tandem Diabetes, Inc.

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Hosted By: San Diego State University

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Main Laboratory: Senior Design Lab at SDSU ECE

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Why this Page is Here

This web site outlines and documents the work and steps required to develop and build a wireless induction charging system and battery fuel gauge. The site includes research topics, development history, and the results we achieved.

Who We Are



David Gutierrez - Project Management



Trevor Behan - Budgeting and Components Management/Selection



Caleb Butler - Technical Reports Editing



Matt Wold - PowerPoint Presentation Editing


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