Variable Gain Reference Antenna for Foreign Object Detection
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Solution Overview
Problem
Non-contact wireless charging systems for vehicles face challenges in detecting foreign objects proximate to the source and capture resonators, which can interfere with electromagnetic energy transmission, necessitating a robust foreign object detection system.
Innovation Solution
A non-contact charging device equipped with a source resonator, foreign object detectors including vertical and horizontal antennas, and a reference antenna with a variable gain amplifier to enhance detection sensitivity and signal analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reference antenna is used to detect electromagnetic energy from the source resonator, then the ability to detect foreign objects is improved, but the sensitivity to foreign objects increases causing false detections
Solution Approach 1:
The patent applies a variable gain amplifier that dynamically adjusts its amplification factor based on the detected signal strength. When the reference antenna detects strong electromagnetic energy (indicating potential foreign object), the amplifier reduces gain to prevent saturation and false readings. When signal strength is weak, the amplifier increases gain to maintain detection sensitivity. This dynamic adjustment resolves the contradiction between maintaining high sensitivity and avoiding false detections.
Solution Approach 2:
The system changes the operational parameter (amplifier gain) based on the detected signal conditions. By monitoring the raw signal level from the reference antenna and adjusting the amplification factor accordingly, the system adapts its detection threshold to maintain optimal performance across varying electromagnetic environments, preventing both missed detections and false alarms.
2Measurement precision
If the reference antenna is made highly sensitive to detect foreign objects, then detection capability is improved, but the antenna becomes overly sensitive to normal electromagnetic variations causing false alarms
Solution Approach 1:
The system implements a feedback mechanism where the detected signal strength from the reference antenna is continuously monitored and used to adjust the amplifier gain in real-time. This closed-loop control allows the system to distinguish between normal electromagnetic variations (which produce consistent signal patterns) and actual foreign objects (which produce anomalous patterns), reducing false alarms while maintaining detection capability.
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
Effectively detects foreign objects in various orientations and optimizes reference signal amplification for improved foreign object detection and energy transmission efficiency, ensuring safe and efficient charging operations.
Implementation Method 1
The source resonator is configured to transfer electrical energy to a capture resonator in a vehicle
Implementation Method 2
The reference antenna is configured to detect a reference signal originating from the source resonator
Data Source
Figure 1
Figure 2
AI summary
A non-contact charging device (16) for charging a battery (22) includes a source resonator (30), a reference antenna (52), and a variable gain amplifier (56). The source resonator (30) is configured to transfer electrical energy to a capture resonator (20) in a vehicle (12). The reference antenna (52) is configured to detect a reference signal (54) originating from the source resonator (30). The reference antenna (52) is configured to be less sensitive to a presence of a foreign object (36) than a foreign object (36) detection (FOD) antenna proximate to the reference antenna (52). The variable gain amplifier (56) is configured to amplify a reference signal (54) from the reference antenna (52).