Wire-Wound Sensing Coils for Foreign Object Detection in EV Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inductive wireless charging systems for electric vehicles face challenges in detecting foreign objects within the high magnetic field region, which can lead to undesirable induction heating and safety concerns, and in detecting living objects exposed to electromagnetic fields exceeding safety limits.
Innovation Solution
A wire-wound structure configured for electromagnetic sensing, integrated with a detection circuit to measure electrical characteristics and determine the presence of objects, is used in conjunction with a coil-former to form and hold the wire-wound structures, enabling both inductive and capacitive sensing for foreign and living object detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If inductive wireless power transfer is used to enable wireless charging, then power transfer efficiency is improved, but foreign objects in the magnetic field region experience undesirable induction heating
Solution Approach 1:
The patent implements foreign object detection before initiating power transfer by measuring electrical characteristics (impedance, Q-factor) of sense coils. This preliminary detection identifies foreign objects in the magnetic field region, allowing the system to prevent or adjust power transfer to avoid induction heating of detected objects.
Solution Approach 2:
The system continuously monitors electrical characteristics of sense coils during operation and compares them against reference values or thresholds. When changes indicate foreign object presence, the system provides feedback to control the power transfer process, adjusting or stopping transmission to prevent harmful induction heating while maintaining efficient power transfer when safe.
2Reliability
If foreign object detection is implemented to prevent induction heating, then safety is improved, but system complexity increases
Solution Approach 1:
The patent integrates foreign object detection functionality into the existing wireless power transfer system by using sense coils that share the same physical structure and electrical connection infrastructure as the power transfer coils. The detection circuit leverages the inherent electrical characteristics of the coils, merging safety detection with power transmission functions to minimize additional system complexity.
Solution Approach 2:
The sense coils serve dual purposes: they are part of the power transfer structure and simultaneously function as sensing elements for foreign object detection. This multi-functionality allows the system to achieve both power transmission and safety detection without requiring completely separate dedicated detection hardware, thereby limiting the increase in system complexity.
3Measurement precision
If sense coils are integrated into the wireless power transfer structure, then detection capability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent uses sense coils with the same construction, materials, and integration method as the power transfer coils. Both are implemented as planar spiral or rectangular coils using identical fabrication processes, ensuring homogeneous manufacturing procedures that simplify production despite the added detection functionality.
Solution Approach 2:
The system distinguishes between power transfer and foreign object detection by operating the sense coils at different frequencies or measuring different electrical parameters (impedance, Q-factor). This parameter-based differentiation allows a single physical coil structure to serve both functions without requiring separate manufacturing processes for different coil types.
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 detects foreign and living objects within the inductive wireless power transfer system, enhancing safety by preventing induction heating and ensuring compliance with electromagnetic field exposure limits, while potentially reducing production costs through advanced manufacturing processes.
Implementation Method 1
a first electrically conductive wire-wound structure configured for electromagnetic sensing of the object in a predetermined area
Implementation Method 2
an alternating current passing through the coil e.g., of a primary wireless power transfer structure produces an alternating magnetic field. When a secondary wireless power transfer structure is placed in proximity to the primary wireless power transfer structure, the alternating magnetic field induces an electromotive force (EMF) into the coil of a secondary wireless power transfer structure
Implementation Method 3
The resonant structure may comprise a capacitively loaded inductor forming a resonance substantially at a fundamental operating frequency of the inductive WPT system
Data Source
AI summary
This disclosure provides an apparatus for detecting a presence of an object in a predetermined area of an inductive wireless power transfer system. The apparatus comprises a first wire-wound structure having an electrical characteristic configured for electromagnetic sensing of the object. The first wire-wound structure is formed, carried, and held in place by a coil-former substantially from a non-conductive material. The coil-former also forms, carries, and holds in place a second wire-wound structure configured for transferring power inductively. The apparatus further comprises a detection circuit coupled to the first wire-wound structure and configured to measure the electrical characteristic of the first wire-wound structure and to detect the presence of the object in response to a change in the electrical characteristic.