Passive Beacon Positioning in EV Wireless Charging FOD Loops
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Solution Overview
Problem
Misalignment between a vehicle power-transfer system and a base power-transfer system in wireless power-transfer systems negatively affects the efficiency of power transfer to electric vehicles, as existing alignment systems are inadequate in ensuring precise positioning.
Innovation Solution
A hybrid foreign-object detection and positioning system is introduced, utilizing a passive beacon integrated into the electric vehicle that interacts with a foreign object detection system, providing guidance and positioning information through a resonant circuit and modulation of impedance states to enhance alignment efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a passive beacon is integrated into the electric vehicle for positioning, then positioning accuracy is improved, but the risk of false detection with foreign objects increases
Solution Approach 1:
The patent applies modulation frequency as a distinctive 'signal color' to differentiate the passive beacon from foreign objects. The beacon loop modulates its impedance at a specific frequency range (1-10 kHz) that is distinct from the resonant frequencies of typical foreign objects, allowing the FOD system to identify and filter out beacon signals while maintaining sensitivity to actual foreign objects
Solution Approach 2:
The system implements a feedback mechanism where the FOD system continuously monitors impedance changes and uses signal processing to distinguish between beacon-modulated signals and foreign object signals. The system adjusts its detection parameters based on the detected modulation patterns, enabling reliable differentiation between the intentional beacon and unintentional foreign objects
2Device complexity
If the FOD system detects both foreign objects and passive beacon using the same sense loops, then system complexity is reduced, but detection accuracy deteriorates
Solution Approach 1:
The passive beacon implements periodic modulation of its impedance state at a specific frequency range (1-10 kHz), creating a time-varying signal pattern that distinguishes it from static foreign objects. This periodic action allows the FOD system to use frequency-domain analysis to separate beacon signals from foreign object signals in the same sense loops
Solution Approach 2:
The system transitions from static impedance detection to dynamic impedance modulation detection. The beacon loop's impedance is dynamically modulated in response to the wireless power transfer magnetic field, creating a time-varying signature that the FOD system can track and differentiate from the static or differently-patterned signatures of foreign objects
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
The system effectively determines the position of the electric vehicle relative to the base power-transfer system, improving power transfer efficiency by distinguishing the passive beacon from foreign objects and providing accurate positioning data for alignment, thereby enhancing the alignment process.
Implementation Method 1
The resonant circuit is configured to resonate based on a magnetic field generated by each of the one or more FOD sense loops
Implementation Method 2
The beacon loop is magnetically coupled with one or more foreign object detection (FOD) sense loops
Implementation Method 3
The resonant circuit is electrically connected to a transistor configured to modulate an impedance state of the passive beacon circuit
Data Source
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AI summary
An apparatus is disclosed for a hybrid foreign-object detection and position system. In an example aspect, a foreign object detection (FOD) system of the base power-transfer system detects a passive beacon of an electric vehicle power- transfer system based on a beacon loop of the passive beacon overlapping an array of FOD sense loops effective to cause a change in impedance or admittance of one or more of the FOD sense loops. In aspects, the impedance reflects a modulation signal from the passive beacon. A position detection system integrated with the FOD system determines a passive beacon response in the input data based on the modulation frequency from the passive beacon. Then, a position of the beacon loop is determined relative to the array of FOD sense loops using a result of the passive beacon response canceled from input data.