Wireless Charging Pad Coil Layout for Foreign Object Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Wireless power transfer systems face inefficiencies and safety risks due to the induction of eddy currents in foreign objects, such as metallic objects, when a magnetic field is provided without a suitable receiver, leading to inappropriate power delivery and potential fires.
Innovation Solution
A wireless power transfer pad with decoupled detection coils and power transfer coils, where detection coils are configured to detect changes in voltage and trigger a circuit output to identify foreign objects, ensuring only appropriate loads receive power, and the magnetic field generated by detection coils ceases when a metal object tries to draw power, preventing heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmitter provides a magnetic field without an appropriate receiver, then the magnetic field is available to couple with any object, but eddy currents are induced in foreign objects causing inefficiency and safety risks
Solution Approach 1:
A detection coil is introduced as an intermediary element between the power transfer coil and foreign objects. The detection coil generates a magnetic field that interacts with foreign objects to produce detectable signals, allowing the system to identify and respond to the presence of foreign objects before power transfer occurs, thereby preventing eddy current induction while maintaining magnetic field availability for legitimate receivers
Solution Approach 2:
The system implements feedback by continuously monitoring the magnetic field environment using the detection coil. When the detection coil senses changes indicative of foreign object presence (such as unexpected eddy current signatures), the system responds by preventing or reducing power transfer from the power transfer coil, thus eliminating the harmful effect while preserving the ability to provide power when appropriate
2Reliability
If detection coils are added to detect foreign objects, then foreign object detection capability is improved, but device complexity increases
Solution Approach 1:
The detection coil is designed to perform multiple functions: it detects foreign objects through eddy current signatures, verifies the presence of appropriate receivers, and provides information for power transfer control. This multi-functionality allows a single additional component to address multiple system requirements, improving reliability without proportionally increasing complexity
Solution Approach 2:
The magnetic field detection function is segmented from the power transfer function by using separate coils. The detection coil handles foreign object detection while the power transfer coil handles power delivery. This segmentation allows each coil to be optimized for its specific function and enables independent control, improving detection reliability while keeping the overall system architecture manageable through functional separation
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 solution effectively distinguishes between intended receivers and foreign objects, ensuring efficient power transfer while preventing overheating and safety hazards, thereby enhancing the reliability and safety of wireless power transfer systems.
Implementation Method 1
a detection coil configured to generate a magnetic field
Implementation Method 2
eddy currents can be induced in the object
Implementation Method 3
a primary or transmitter apparatus to make a magnetic field available to couple with a secondary or receiver apparatus
Data Source
AI summary
A wireless power transfer pad has at least one power transfer coil and a plurality of foreign object detection coils. Each foreign object detection coil is decoupled from its neighboring detection coils and is also decoupled from the power transfer coil.