Wireless Charging Coil Position Sensing for Precise Foreign Object Detection
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Solution Overview
Problem
Current foreign object detection in wireless charging technologies does not accurately consider the relative position between the transmit and receive ends, leading to inefficiencies and safety hazards due to eddy current losses and heat generation from metal foreign objects.
Innovation Solution
A wireless charging apparatus and method that uses resonant networks and power conversion circuits to accurately determine the relative position by measuring self-inductance, coupling coefficient, and coil mutual inductance, enabling precise foreign object detection and reducing errors in power loss calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If foreign object detection is performed without considering relative position, then detection process is simple, but detection accuracy is low
Solution Approach 1:
The system performs preliminary detection of self-inductance, coupling coefficient, and coil mutual inductance to determine relative position before conducting foreign object detection. This preliminary action enables accurate FOD by establishing the spatial relationship between transmit and receive coils, allowing the system to account for position-dependent variations in electromagnetic coupling and reduce false detections.
2Measurement precision
If relative position is accurately measured using multiple parameters, then foreign object detection accuracy is improved, but measurement complexity increases
Solution Approach 1:
The system measures self-inductance, coupling coefficient, and coil mutual inductance to obtain feedback information about the relative position between transmit and receive coils. This feedback is used to dynamically adjust the foreign object detection threshold and interpretation, enabling accurate detection despite variations in coupling conditions caused by different relative positions.
3Reliability
If foreign object detection does not account for relative position, then detection speed is fast, but safety risks increase due to undetected eddy current losses
Solution Approach 1:
The system performs preliminary measurement of electromagnetic parameters (self-inductance, coupling coefficient, coil mutual inductance) to establish relative position before foreign object detection. This enables the system to quickly determine appropriate detection thresholds based on position, maintaining fast detection speed while improving safety reliability by accounting for position-dependent eddy current loss characteristics.
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 solution improves foreign object detection accuracy by accounting for relative positions, reducing errors in power loss calculations, and enhancing safety by preventing overheating and potential fires.
Implementation Method 1
A principle of a wireless charging technology is to transmit electric energy through magnetic field coupling between a transmitting coil at a transmit end and a receiving coil at a receive end
Implementation Method 2
an alternating current magnetic field generated between the transmit end and the receive end may generate eddy current losses and heat in the metal foreign object
Implementation Method 3
The resonant network is configured to perform impedance matching
Implementation Method 4
transferring electric power from the power transfer coil to the power reception coil by electromagnetic induction
Data Source
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AI summary
This application discloses a wireless charging apparatus, a position detection method, and a system. The apparatus includes a transceiver end (100), and the transceiver end (100) includes a resonant network and a power conversion circuit. The apparatus further includes a controller (200). The controller (200) is configured to obtain a relative position between a transmit end (101) and a receive end (102) based on a self-inductance of a transmitting coil and at least one parameter, where the at least one parameter includes one or two of a coupling coefficient between the transmitting coil and a receiving coil and a coil mutual inductance between the transmitting coil and the receiving coil. There is a single change relationship, namely, a monotonous change relationship, between the self-inductance of the transmitting coil, the coupling coefficient, and the relative position, and there is also a single change relationship between the self-inductance of the transmitting coil, the coil mutual inductance, and the relative position. Therefore, the relative position between the transmit end (101) and the receive end (102) of wireless charging can be accurately detected by using the self-inductance of the transmitting coil and at least one of the coupling coefficient and the coil mutual inductance.