Low Frequency RFID Sensor Coupling Through Conductive Surfaces
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Solution Overview
Problem
Embedded RFID sensors in gas turbine engines with metallic components face difficulties in wireless communication due to eddy currents induced by conductive surfaces, making it challenging for external readers to penetrate and read sensor data effectively.
Innovation Solution
A magnetic communication system is implemented, using a low-frequency RFID chip with a coupling circuit and coil winding within a ferromagnetic p-core, allowing concentrated magnetic flux to penetrate through conductive components and couple with an external reader system, enabling wireless power transfer and data communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RFID sensors operate at tens or hundreds of MHz frequencies, then wireless communication capability is achieved, but eddy currents are induced in conductive surfaces that prevent magnetic field penetration and reduce reading effectiveness
Solution Approach 1:
The patent changes the operating frequency parameter from tens or hundreds of MHz to low frequency (125 kHz or below). This parameter change reduces the induction of eddy currents in conductive surfaces while maintaining wireless communication capability through magnetic field coupling, directly resolving the contradiction between communication reliability and eddy current interference
Solution Approach 2:
The patent introduces a magnetic coupling intermediary system consisting of a magnetic field generator in the reader and a magnetic field sensor in the tag. This intermediary magnetic coupling mechanism enables wireless communication at low frequencies without inducing significant eddy currents in conductive surfaces, allowing RFID tags to function on metallic surfaces like aircraft skins
2Reliability
If RFID sensors are embedded underneath metallic surfaces, then sensor protection and integration are improved, but magnetic field penetration is blocked by eddy currents making reading nearly impossible
Solution Approach 1:
By changing the operating frequency to low frequency (125 kHz or below), the magnetic fields can penetrate through metallic surfaces and housings without inducing significant eddy currents. This allows embedded sensors to be read wirelessly from outside the component while maintaining their protective embedding, resolving the contradiction between sensor integration and magnetic field penetration
3Object-affected harmful factors
If low frequency RFID is used to reduce eddy currents, then magnetic field penetration through conductive surfaces is improved, but coupling circuit complexity increases
Solution Approach 1:
The system uses the existing magnetic field characteristics of low frequency RFID to achieve penetration through conductive surfaces. The magnetic coupling mechanism naturally provides the needed field strength and penetration capability without requiring additional active components or complex circuitry, allowing the system to serve itself and avoid increased complexity
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 effectively reduces eddy currents, allowing reliable wireless communication and power transfer between the sensor system and external reader, even in conductive components like aircraft skins or turbine blades, enhancing maintenance and performance monitoring.
Implementation Method 1
the first core comprises a p-core shape (pot-core) such that it includes a first outer wall circumscribing a first inner pillar that extends from a first base of the first core, the first core is a ferromagnetic material
Implementation Method 2
the sensor system produces a magnetic flux that is concentrated and directed by a first core of the sensor system to penetrate through the conductive component
Implementation Method 3
a first coil winding wound within a first core, the first coil winding being operatively associated with a low frequency magnetic flux
Implementation Method 4
the operating frequency of tens or hundreds of MHz interacts with the conductive surfaces to create eddy currents that prevent significant magnetic field penetration through the conductive surface
Data Source
Figure 1
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Figure 3~5
AI summary
A magnetic communication system for a gas turbine engine (10) may include a sensor (42) coupled (58) to a microcontroller (43). A low frequency radio-frequency identification integrated chip (44) may be coupled (60) to the microcontroller. A first coupling circuit (62) may be coupled (78, 82) to the low frequency radio-frequency identification integrated chip and may include a first coil winding (90) wound within a first core (39). The first coil winding may be operatively associated with a low frequency magnetic flux.