Wireless Power Coil Array Foreign Object Detection
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Solution Overview
Problem
Existing wireless power transmission systems face challenges in accurately detecting foreign objects near coils due to unnecessary resonance modes, which decrease object detection sensitivity and can lead to overheating.
Innovation Solution
A foreign object detecting device with a coil array, short-circuit switches, selection switches, a detecting circuit, and a control circuit that manages electrical connections to suppress unnecessary resonance by reducing inductance between coils, allowing for sensitive detection of objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a coil array is used for wireless power transmission, then power transmission capability is improved, but unnecessary resonance modes occur which decrease object detection sensitivity
Solution Approach 1:
The patent divides the coil array into multiple individual coils, each with its own short-circuit switch and selection switch. This segmentation allows independent control of each coil's resonance state, enabling the system to suppress unnecessary resonance modes while maintaining power transmission capability through coordinated operation of multiple coils.
Solution Approach 2:
The patent changes the electrical parameters (impedance, resonance frequency) of individual coils by using short-circuit switches to alter the circuit configuration. By adjusting these parameters dynamically, the system can eliminate unnecessary resonance modes that interfere with object detection while preserving the desired magnetic field for power transmission.
2Productivity
If multiple coils are operated simultaneously for power transmission, then transmission efficiency is improved, but resonance interference increases making object detection difficult
Solution Approach 1:
The patent implements periodic switching of coils using selection switches, where coils are activated in sequences or patterns rather than continuously simultaneously. This periodic action allows the system to maintain high power transmission efficiency through multiple coils while creating time windows where resonance interference is minimized, enabling object detection.
Solution Approach 2:
The patent introduces selection switches and short-circuit switches as intermediary control elements between the power source and coils. These intermediaries manage the operational state of each coil, coordinating their activation to achieve efficient power transmission while suppressing resonance interference that would otherwise obscure object detection signals.
3Measurement precision
If coil impedance changes are monitored for object detection, then detection capability is improved, but resonance modes cause false readings
Solution Approach 1:
The patent applies different control strategies to different coils within the array. By using individual short-circuit switches for each coil, the system can locally adjust the impedance and resonance characteristics of specific coils to minimize interference, while monitoring impedance changes in other coils for object detection, thereby improving both detection capability and reliability.
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 effectively suppresses unnecessary resonance and enhances object detection sensitivity, ensuring safe and efficient wireless power transmission by accurately identifying objects near the coil array.
Implementation Method 1
a wireless power transmission system includes a power transmitting device provided with a power transmitting coil (power transmission antenna) and a power receiving device provided with a power receiving coil (power reception antenna). The wireless power transmission system transmits power, without making electrodes directly come into contact with each other, by capturing a magnetic field generated by the power transmitting coil using the power receiving coil.
Implementation Method 2
a detecting circuit that detects an amount of change, from a predetermined reference value, in a physical value that changes in accordance with a change in impedance of each of the coils
Implementation Method 3
short-circuit switches, each of which is connected in parallel with each of the coils and each of which establishes or breaks an electrical connection between both ends of the coil
Data Source
AI summary
An object detecting device includes a coil array including coils, short-circuit switches connected in parallel with the coils, an oscillator circuit that outputs, to the coils, a voltage including an alternating current component, selection switches connected between the coils and the oscillator circuit, a detecting circuit that detects an object based on a change in a physical value such as voltage, and a control circuit that opens and closes the short-circuit switches and the selection switches. When a first selection switch is closed, a first short-circuit switch, which is connected to the first selection switch, is opened. The other selection switches are opened, and the other short-circuit switches are closed.