Wireless Charging Loss Modeling for Accurate Foreign Object Detection
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Solution Overview
Problem
Accurately estimating friendly metal losses in wireless power transfer systems is complicated by unknown parameters such as relative positioning of devices, leading to potential inefficiencies and undesirable user experiences due to inaccurate foreign object detection.
Innovation Solution
A wireless power transfer device employs a controller and communication circuitry to estimate friendly metal losses using modeling parameters, including coefficients related to current and voltage, and adjusts power transfer based on these estimates to improve foreign object detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional foreign object detection methods are used without accurate friendly metal loss estimation, then the system is simpler to implement, but foreign object detection accuracy deteriorates due to inability to distinguish between friendly metal losses and foreign object losses
Solution Approach 1:
The system performs preliminary characterization of friendly metal losses by measuring power losses at different coupling factors before actual foreign object detection. These measurements are stored as lookup table entries that are later used to accurately distinguish friendly metal losses from foreign object losses, improving detection accuracy without adding complexity during operation
Solution Approach 2:
The patent introduces coupling factor as an intermediary parameter to characterize the wireless power transfer conditions. By using coupling factor to index into pre-computed lookup tables, the system can accurately estimate friendly metal losses under varying conditions without requiring complex real-time calculations, thus improving measurement precision while maintaining manageable system complexity
2Measurement precision
If the system accounts for varying coupling conditions with multiple coefficients, then foreign object detection accuracy improves, but the number of parameters to manage increases
Solution Approach 1:
The system pre-computes and stores friendly metal loss characteristics in lookup tables during system initialization or characterization phase. These tables contain pre-calculated coefficients for different coupling factors, eliminating the need to manage and process multiple parameters in real-time, thus improving accuracy while reducing operational complexity
Solution Approach 2:
The patent creates simplified representations of complex friendly metal loss characteristics by copying them into pre-computed lookup tables. Instead of managing multiple coefficients and performing complex calculations, the system uses pre-stored values that can be quickly retrieved based on coupling factor, maintaining accuracy while simplifying parameter management
3Productivity
If the system uses pre-computed lookup tables for friendly metal loss estimation, then foreign object detection speed improves, but memory requirements increase
Solution Approach 1:
The system performs the computationally intensive task of computing friendly metal loss characteristics in advance and stores the results in compact lookup tables. This preliminary computation allows for rapid foreign object detection during operation by simply retrieving pre-computed values, improving detection speed while keeping memory requirements manageable through efficient data storage
Solution Approach 2:
The patent optimizes the storage format and granularity of the lookup tables by using parameter changes - storing values at discrete coupling factor points rather than continuous data. This approach maintains detection accuracy while minimizing memory usage, as the system only needs to store values at key operating points rather than all possible conditions
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
Enhances the accuracy of foreign object detection, preventing unnecessary power delivery to foreign objects and optimizing power transfer efficiency by accounting for varying coupling conditions.
Implementation Method 1
A wireless power transfer device may include a coil that couples to a corresponding coil of a counterpart device to facilitate wireless power transfer
Data Source
AI summary
A wireless power transfer device can include a coil that couples to a corresponding coil of a counterpart device to facilitate wireless power transfer, a power converter coupled to the coil, and controller and communication circuitry that monitors one or more observable parameters associated with the wireless power transfer to detect a presence of a foreign object that is not the counterpart device and control the power converter responsive to detection of a foreign object. The controller and communication circuitry can perform foreign object detection based on power accounting that includes estimating friendly metal losses associated with the counterpart device. The controller and communication circuitry can receive from the counterpart device friendly metal loss modeling parameters associated with the counterpart device, the modeling parameters including one or more coefficients relating to a wireless power transfer current and one or more coefficients relating to a wireless power transfer voltage.