Wireless Power Transfer Foreign Object Detection via Field Reconstruction
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Solution Overview
Problem
Existing wireless power transfer systems face challenges in detecting foreign objects, which can cause overheating and fires due to eddy currents, and current methods are not effective in ensuring safety during magnetic wireless power transfer, particularly in electric vehicle charging.
Innovation Solution
A system utilizing multiple sensors and a processor to estimate terminal variable levels and detect foreign objects by comparing sensor data-generated field assessments, employing an electromagnetic model-based approach that reconstructs transmitter and receiver coil currents and voltages, allowing for invariant detection across various power levels and misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foreign object detection is implemented using conventional methods (induced voltage differences, impedance sensing, quality factor measurement), then foreign object detection capability is provided, but detection reliability is insufficient under varying power levels and coil misalignments
Solution Approach 1:
The patent replaces conventional electrical sensing methods (voltage, impedance, quality factor) with an electromagnetic field-based detection system. Multiple sensors measure the electromagnetic field directly, and a processor reconstructs terminal variables (current, voltage, power) from these field measurements. This substitution enables detection that is invariant to power level changes and coil misalignment, as the electromagnetic field measurements capture the actual physical state regardless of system configuration variations.
Solution Approach 2:
The electromagnetic field sensing system serves multiple functions: it detects foreign objects, measures terminal variables (current, voltage, power), and operates across varying power levels and misalignment conditions. The same sensor array and processing algorithm provide comprehensive system monitoring and safety detection, making the system universally applicable across different operating conditions without requiring separate detection mechanisms.
2Reliability
If multiple sensors and electromagnetic field reconstruction are used to achieve invariant detection, then detection robustness and dynamic range are improved, but device complexity increases
Solution Approach 1:
The patent introduces electromagnetic field measurements as an intermediary between the wireless power transfer system and the detection algorithm. Instead of directly measuring electrical parameters that vary with system configuration, the system measures the electromagnetic field (which directly reflects the physical state) and reconstructs terminal variables from these measurements. This intermediary approach simplifies the detection logic while improving robustness, as the field measurements provide a stable reference that is invariant to power level and misalignment changes.
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 provides robust foreign object detection with wide dynamic range, invariance to power levels and coil misalignment, and the ability to detect all foreign objects within the electromagnetic space, ensuring safety and reliability in wireless power transfer systems.
Implementation Method 1
a plurality of sensors, each sensor of the plurality of sensors being positioned relative to the plurality of transfer elements and configured to generate sensor data indicative of a field implementing the wireless power transfer
Implementation Method 2
Foreign objects near magnetic wireless power transfer systems are one hazard because they can heat from eddy currents and cause a fire
Data Source
AI summary
A system for wireless power transfer includes a plurality of transfer elements, each transfer element of the plurality of transfer elements being configured as a transmitter for the wireless power transfer or a receiver for the wireless power transfer, a plurality of sensors, each sensor of the plurality of sensors being positioned relative to the plurality of transfer elements and configured to generate sensor data indicative of a field implementing the wireless power transfer, and a processor coupled to the plurality of sensors and configured to determine an estimate of a terminal variable level in a respective transfer element of the plurality of transfer elements based on the sensor data, and to determine whether a foreign object is affecting the wireless power transfer based on whether the estimated terminal variable level is different from another assessment of the terminal variable level by more than a threshold.