Tesla patents wireless charger that spots metal objects despite temperature changes
Tesla describes a system for wireless charging pads that uses electrical coils to detect if a metal object, like a coin, is sitting on the pad. The system sends signals through the coils to measure changes in electrical properties, specifically looking for a drop in inductance and a rise in resistance. It distinguishes these changes from normal shifts caused by the pad heating up or cooling down.
In the filing’s own words
The present disclosure relates to methods and systems that can reliably detect foreign objects on a wireless charging pad under varying temperatures. In some examples, an object detector can utilize a set of inductive coils included in resonant tanks, and excite the resonant tanks using signals in a range of frequencies including or near a nominal resonant frequency of the resonant tanks. The object detector can detect a metal object based on resistance of a coil increasing and inductance of the coil decreasing. By analyzing the shifts and/or distributions in resonant frequencies and output magnitudes (e.g., output voltage peaks), the object detector can distinguish between changes of frequencies and magnitudes caused by temperature and those caused by foreign objects to accurately detect the foreign objects.
What exactly they claim (claim 1)
1. A wireless charging system comprising: a resonant tank comprising a coil; an exciter electrically connected to the resonant tank; and a processing circuit in communication with at least the exciter, the processing circuit configured to: cause the exciter to excite the resonant tank; determine a first parameter indicative of inductance of the coil and a second parameter indicative of resistance of the coil associated with the coil being excited; and detect an object based on the first parameter indicating a decrease in inductance and the second parameter indicating an increase in resistance relative to when the object is not present.
Facts
- Company
- Tesla (Tesla, Inc.)
- Official title
- OBJECT DETECTION IN WIRELESS CHARGING
- Publication number
- US20260299157A1
- Application number
- 19566418
- Filed
- Mar 13, 2026
- Published
- Oct 1, 2026
- Inventors
- 1
- Claims
- 20
Classified under
G01V 3/101 Physics & computingH02J 50/12 Electricity & electronicsH02J 50/60 Electricity & electronicsMore from Tesla in Batteries & energy
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Summaries are simplified from the filing’s own abstract and first claim. A patent filing is not a product announcement.
Patent data and drawings: U.S. Patent and Trademark Office (USPTO). Nebula is not affiliated with or endorsed by the USPTO.