Non-contact Power Feeding Detection Circuit for Foreign Object Safety
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Solution Overview
Problem
Existing non-contact power feeding systems using magnetic field resonance risk damaging foreign objects with strong magnetic fields and can alter resonant frequencies due to metal components, leading to inefficient power transmission and reception.
Innovation Solution
Incorporating a detection circuit to monitor current amplitude through the power transmission coil and control power transmission based on predetermined ranges, and using a metal plate with an opening portion and a magnetic member to stabilize resonant frequencies in the power reception device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power transmission is performed using a strong magnetic field, then power transmission efficiency is improved, but foreign objects may be damaged due to excessive voltage induction
Solution Approach 1:
The system performs foreign object detection before initiating power transmission by measuring the impedance of the transmission coil. If a foreign object is detected (indicated by impedance outside the predetermined range), the system prevents power transmission from occurring, thereby avoiding voltage induction damage to the foreign object while allowing efficient power transmission when safe
2Strength
If metal components are added to improve structural strength, then device durability is improved, but resonant frequency changes occur affecting power transmission stability
Solution Approach 1:
The system continuously monitors the impedance of the transmission coil during operation and compares it against predetermined ranges. When impedance changes indicate the presence of foreign objects or metal components affecting resonant frequency, the system adjusts or stops power transmission to maintain stability and prevent harmful effects
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
Prevents damage to foreign objects by stopping power transmission when foreign objects are detected and maintains stable resonant frequencies, ensuring efficient and safe power transfer.
Implementation Method 1
An alternating current is then passed through the power transmission-side coil, and thus an alternating magnetic field at the reference frequency is generated in the power transmission-side coil
Implementation Method 2
the alternating magnetic field is transmitted to the power reception-side resonant circuit which resonates at the reference frequency, and thus an alternating current flows through the power reception-side coil
Data Source
AI summary
In a non-contact power feeding system which is formed with a power transmission device having a power transmission-side resonant circuit including a power transmission-side coil and a power reception device having a power reception-side resonant circuit including a power reception-side coil and which can transmit and receive power by a magnetic field resonance method, when the power is transmitted, the power transmission device monitors the amplitude of a current flowing through the power transmission-side coil. Then, when a current amplitude detection value (VmFOD) falls outside a predetermined normal range, it is determined that a foreign object is present, and thus the power transmission is stopped.