Contactless Power Detection via Q-Factor Measurement
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Solution Overview
Problem
Existing contactless power transmission systems face challenges in accurately detecting metal foreign substances near coils without using additional sensors, as previous methods fail to distinguish between metal chassis and foreign substances, leading to inaccurate detection.
Innovation Solution
A detecting device and method that measure the Q-factor of a resonant circuit by superimposing a measurement signal on the power transmission signal and removing it from the alternating-current signal, allowing for accurate detection of metal foreign substances without stopping power transmission and without the need for new sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is used to detect metal foreign substances, then detection capability is improved, but cost increases and design restrictions are imposed
Solution Approach 1:
The system uses its own power transmission signals and existing circuit parameters to detect metal foreign substances, rather than requiring separate detection sensors. The control device monitors changes in power transmission efficiency, impedance, or resonant frequency that occur when metal objects are present, allowing the power transmission system to perform self-diagnosis and detection functions.
2Measurement precision
If an optical sensor is used to detect metal foreign substances, then detection capability is improved, but cost increases
Solution Approach 1:
The control device performs multiple functions using the same hardware components: it controls power transmission to the receiver, monitors power consumption, and detects metal foreign substances by analyzing changes in electrical parameters during normal operation. This multi-functional approach eliminates the need for separate dedicated detection sensors.
3Measurement precision
If Q-factor measurement is performed by stopping power transmission, then measurement accuracy is improved, but productivity decreases
Solution Approach 1:
The system performs brief, periodic measurements of power consumption or electrical parameters during normal power transmission operation. These quick snapshots of data are sufficient to detect metal foreign substances without requiring complete cessation of power transmission, thus maintaining productivity while achieving 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
Enables high-accuracy detection of metal foreign substances while maintaining continuous power transmission, simplifying control flows and reducing redundant measurement times, and is applicable to both electromagnetic induction and magnetic resonance systems.
Implementation Method 1
a coil configured to be electromagnetically coupled to an external; a resonant circuit configured to include at least the coil
Implementation Method 2
the technique called the magnetic resonance system. It has a characteristic that the resonance phenomenon is aggressively utilized and thereby even little magnetic flux is permitted as the magnetic flux shared by the power feed source and the power feed target
Implementation Method 3
if a metal exists between the power transmission side and the power reception side, possibly an eddy current is generated in the metal and heat generation of the metal is caused
Data Source
AI summary
Disclosed herein is a detecting device including a coil electromagnetically coupled to the external, a resonant circuit that includes at least the coil, and a detecting section that superimposes a measurement signal for measuring the Q-factor of the resonant circuit on a power transmission signal transmitted to the coil in a contactless manner and removes the power transmission signal from an alternating-current signal obtained by superimposing the measurement signal on the power transmission signal. The detecting section measures the Q-factor by using the alternating-current signal from which the power transmission signal is removed.