Wireless Charging Coil Q-Value Correction for Foreign Material Detection
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Solution Overview
Problem
Existing non-contact power transmission systems face challenges in accurately detecting metallic foreign materials due to temperature-induced changes in coil resistance and Q-value, which affect detection accuracy and heat generation, especially in portable devices with metal housings.
Innovation Solution
Incorporating a temperature detection unit to correct the Q-value measurements based on coil temperature, reflecting the temperature changes in the resistance value, thereby improving the accuracy of metallic foreign material detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Q-value measurement is used to detect metallic foreign materials, then detection capability is provided, but temperature changes cause resistance value changes that reduce detection accuracy
Solution Approach 1:
The system measures the actual Q-value of the coil at operating temperature and uses this measured value as a reference threshold for metallic foreign material detection. This feedback mechanism allows the detection threshold to automatically adapt to temperature-induced resistance changes, maintaining detection accuracy across varying temperatures.
Solution Approach 2:
The invention changes the detection parameter from a fixed theoretical Q-value to a dynamically measured Q-value that reflects actual operating conditions. By using the measured Q-value as the reference threshold, the system adapts to parameter changes caused by temperature variations, ensuring accurate metallic foreign material detection regardless of thermal conditions.
2Strength
If metal housing is used in portable devices, then device strength and aesthetics are improved, but false positive detection occurs due to eddy current effects in the housing
Solution Approach 1:
The system uses feedback from actual Q-value measurements at operating temperature to establish an adaptive detection threshold. This allows the system to distinguish between Q-value changes caused by the metal housing (which are consistent and measurable) and those caused by metallic foreign materials, reducing false positives while maintaining detection capability.
Solution Approach 2:
The metal housing itself serves as a reference by establishing a baseline Q-value characteristic that the system learns to recognize. The housing's electromagnetic characteristics become part of the normal operating profile, allowing the system to self-adjust and differentiate between normal housing effects and actual foreign material presence.
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 approach enhances the accuracy of detecting metallic foreign materials by accounting for temperature variations, reducing false positives from metal housings and improving the reliability of non-contact power transmission systems.
Implementation Method 1
a temperature detection unit for detecting a temperature of the coil; a sensing unit for measuring a Q value of the circuit including the coil; and a correction unit for correcting the Q value measured by the sensing unit based on temperature information detected by the temperature detection unit
Implementation Method 2
a circuit including at least a coil electromagnetically coupled to an outside
Implementation Method 3
The Q value is an index representing a relationship between energy retention and loss in a circuit having a coil of the power transmission side or the power reception side (indicating the strength of resonance of a resonant circuit)
Data Source
AI summary
There is provided a sensing device including a circuit including at least a coil electromagnetically coupled to an outside; a temperature detection unit for detecting a temperature of the coil; a sensing unit for measuring a Q value of the circuit; and a correction unit for correcting the Q value measured by the sensing unit based on temperature information detected by the temperature detection unit.