Parasitic Coil for Wireless Power Protection
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Solution Overview
Problem
Existing wireless power transmission systems face challenges in efficiently charging devices over reasonable distances and protecting NFC/RFID cards from excessive power, which can lead to overheating and damage due to mismatched frequencies and close antenna spacing requirements.
Innovation Solution
The implementation of a wireless power transfer system using near-field communication and resonant loop antennas, with a protection circuit that generates a magnetic field to oppose excessive power, allowing efficient energy transfer while preventing damage by decoupling from unwanted frequencies and shielding sensitive areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If plane wave radiation coupling is used for wireless power transmission, then power can be transmitted over larger distances, but power coupling efficiency decreases quickly with distance and unintentional radiation interference occurs
Solution Approach 1:
The patent changes the operating parameters by using resonant frequency matching between transmit and receive loop antennas. This resonance condition creates strong magnetic coupling that maintains high power transfer efficiency over distances much larger than traditional inductive coupling, resolving the contradiction between transmission distance and coupling efficiency
Solution Approach 2:
The protection circuit is designed to perform multiple functions: it detects excessive power conditions, generates opposing magnetic fields to cancel harmful radiation, and protects both NFC/RFID cards and wireless power reception. This multi-functionality addresses both the efficiency and interference problems simultaneously
2Adaptability or versatility
If inductive coupling between transmit and receive antennas is used, then multiple devices can be charged simultaneously, but the spacing between antennas must be very close and the charging area is limited
Solution Approach 1:
The patent uses resonant frequency matching to extend the effective coupling distance between antennas. This allows devices to be charged simultaneously at larger spacings while maintaining efficient power transfer, resolving the contradiction between multi-device capability and antenna spacing requirements
3Adaptability or versatility
If NFC or RFID cards are placed within wireless power transmitter charging area, then the cards may receive excessive power from the transmitter, but this can result in loss of power to intended devices and damage the card due to overheating
Solution Approach 1:
The protection circuit continuously monitors the magnetic field environment and, upon detecting excessive power transmission conditions, preemptively generates an opposing magnetic field to cancel the harmful field before it can damage the NFC/RFID card. This preliminary protective action prevents overheating while allowing coexistence with wireless power transmission
Solution Approach 2:
The protection circuit uses the same electromagnetic induction principle that enables wireless power transfer to generate a protective opposing field. By converting the harmful excessive magnetic field into a beneficial protective mechanism, the system eliminates damage risks while maintaining wireless power functionality
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient wireless power transfer over larger areas while protecting NFC/RFID cards from excessive power, ensuring safe operation and preventing overheating by decoupling from non-operational frequencies and shielding sensitive regions.
Implementation Method 1
Other approaches are based on inductive coupling between a transmit antenna embedded, for example, in a 'charging' mat or surface and a receive antenna plus rectifying circuit embedded in the host device to be charged
Implementation Method 2
Antennas are generally of resonant length in order to improve the coupling efficiency
Implementation Method 3
A protection circuit is configured to generate a magnetic field to oppose a magnetic field generated by a wireless power transmitter
Data Source
AI summary
Exemplary embodiments are directed to a device include a parasitic coil for protection of the device. A device may include a first circuit configured to receive a first transmitted signal at an operational frequency. The device may also include a second circuit a second circuit configured to generate a field that opposes at least one of an undesirable portion of a wireless power field of the first transmitted signal and a portion of another wireless power field proximate the first circuit, the another wireless power field generated by a second transmitted signal at a non-operational frequency of the first circuit.