Multipurpose Detection Circuit for EV Wireless Charging Alignment
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Solution Overview
Problem
Inductive wireless power transfer systems for electric vehicle charging face challenges in detecting foreign metallic and living objects, determining vehicle presence and position, and ensuring efficient alignment, which can lead to induction heating and electromagnetic exposure issues.
Innovation Solution
A multi-purpose detection circuit combining inductive and capacitive sense circuits with impedance measurement and time/space-differential detection schemes to detect metallic and living objects, determine vehicle presence and position, and ensure alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If inductive wireless power transfer is used for electric vehicle charging, then power transfer efficiency is improved, but foreign objects and living objects in the power region are exposed to high magnetic field levels causing induction heating and electromagnetic exposure issues
Solution Approach 1:
The system performs foreign object detection (FOD) and living object detection (LOD) before initiating wireless power transfer. By detecting the presence of metallic or living objects in advance using inductive and capacitive sense circuits, the system can prevent harmful induction heating and electromagnetic exposure before they occur, while still enabling efficient power transfer when safe
Solution Approach 2:
The system continuously monitors the inductive power region during charging operation using sense circuits that detect changes in electrical characteristics. This feedback mechanism allows real-time detection of foreign objects and living objects, enabling the system to adjust or terminate power transfer to prevent induction heating and electromagnetic exposure while maintaining efficiency during normal operation
2Measurement precision
If separate detection circuits are used for foreign object detection, living object detection, vehicle detection, and position determination, then detection accuracy is improved, but hardware complexity and costs increase
Solution Approach 1:
The patent implements a multi-purpose detection circuit that performs foreign object detection, living object detection, vehicle detection, and position determination using shared inductive and capacitive sense circuits. By making the sense circuits universal and configurable through software control, the system achieves multiple detection functions with a single hardware platform, reducing complexity and costs while maintaining detection accuracy through specialized detection algorithms for each function
3Reliability
If multiple separate detection systems are implemented for FOD, LOD, VD, and PD functions, then each detection function can be optimized, but the overall system complexity and manufacturing costs increase
Solution Approach 1:
The system merges foreign object detection, living object detection, vehicle detection, and position determination functions into a single integrated detection platform. By combining the inductive and capacitive sense circuits to serve multiple detection purposes and using a unified measurement and control system, the patent reduces manufacturing complexity and costs while maintaining the reliability of each detection function through dedicated processing algorithms
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
Effectively detects and differentiates between metallic and living objects, identifies vehicle type and position, and enhances alignment efficiency, reducing hardware complexity and costs.
Implementation Method 1
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 secondary wireless power transfer structure
Implementation Method 2
In certain applications for inductive wireless charging of electric vehicles, it may also be useful to be able to detect living objects that may be present within or near an inductive power region where the level of electromagnetic field exposure exceeds certain limits
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 (e.g., in the range from 80 kHz to 90 kHz)
Data Source
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AI summary
A multi-purpose detection circuit for object detection and vehicle position determination is described. For example, the circuit is configurable for detecting foreign metallic objects, living objects, and a vehicle or type of vehicle above an inductive wireless power transmitter. The circuit is also configurable for determining the vehicle's position relative to the inductive wireless power transmitter. An example apparatus includes a measurement circuit including a multiplexer, electrically connected to a plurality of inductive and capacitive sense circuits, for measuring one or more electrical characteristics in each of the inductive and capacitive sense circuits according to a predetermined time multiplexing scheme. The apparatus further includes a control and evaluation circuit for evaluating the measured electrical characteristics and determining at least one of a presence of a metallic object, a living object, a vehicle, or a type of vehicle, and a vehicle position based on changes in the measured electrical characteristics.