Capacitive Object Detection in EV Wireless Charging Shields
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Solution Overview
Problem
Current wireless charging systems for electric vehicles lack control over charging based on external factors and fail to detect objects within the charging region, which can disrupt the charging process and pose safety risks.
Innovation Solution
A device and method that utilize an electromagnetic shield with capacitive sensing electrodes to detect changes in capacitance values, allowing for adjustment or termination of charging and identification of objects within the charging region, coupled with thermal gradient monitoring to ensure safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sensing is used to detect objects in the charging region, then object detection capability is improved, but the system complexity increases due to additional sensing circuitry and electrode design requirements
Solution Approach 1:
The electromagnetic shield serves dual functions: it provides electromagnetic shielding during wireless charging and acts as a capacitive sensing electrode for object detection. This multi-functionality eliminates the need for separate sensing electrodes and reduces system complexity while maintaining reliable object detection capability.
Solution Approach 2:
The patent combines the electromagnetic shielding function and the object detection function into a single integrated structure. The shield is electrically connected to a capacitance sensing circuit, merging two previously separate systems into one unified component that performs both protection and detection.
2Device complexity
If the electromagnetic shield is used for both shielding and sensing, then device complexity is reduced, but the sensing precision may be affected by the shield's primary electromagnetic function
Solution Approach 1:
The electromagnetic shield is divided into multiple segments or zones, with specific regions optimized for shielding and others for sensing. This segmentation allows the shield to perform both functions effectively while minimizing interference between the electromagnetic field generation and capacitance measurement processes.
Solution Approach 2:
Different portions of the electromagnetic shield have different functional characteristics. Certain areas are designed with properties optimized for electromagnetic shielding while other areas are configured for sensitive capacitance detection, allowing each region to excel at its primary function without compromising the other.
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 system effectively detects objects within the charging region, adjusts the charging process, and alerts the driver, thereby preventing disruptions and ensuring safe and efficient wireless charging of electric vehicles.
Implementation Method 1
measuring the capacitance value of an electromagnetic shield disposed on the underside of the vehicle. The capacitance value may be monitored by the controller and a change in the capacitance value may be detected when the object enters the wireless charging region.
Implementation Method 2
when a dielectric material (e.g., a material with high permittivity) is placed between the conductors, the capacitance may increase. Accordingly, the voltage differential may decrease without changing (e.g., adjusting) the charge, thus producing a higher capacitance.
Implementation Method 3
a parallel plate capacitor enables two conductors to store an electrical field between the plates. For example, one parallel plate may have a V+ charge and the other parallel plate may have a V− charge.
Implementation Method 4
The dielectric material polarizes and creates an induced electrical field in the opposite direction of the applied electrical field.
Data Source
AI summary
An assembly and method are provided for detecting an object within a wireless charging region of an electric vehicle. The method includes applying by a controller, a voltage to the wireless charging region to generate a capacitance value and measuring by the controller, the capacitance value of an electromagnetic shield disposed on the underside of the vehicle. Further, the controller monitors the capacitance value of the electromagnetic shield; and the controller detects a change in the capacitance value when the object enters the wireless charging region.