Wireless Power FOD Using Friendly Metal Loss Estimation
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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 and variations between devices, which can lead to inefficient power delivery and unnecessary mitigation measures.
Innovation Solution
A wireless power transfer device with controller and communication circuitry that estimates friendly metal losses using modeling parameters, including coefficients related to current and voltage, and performs foreign object detection by subtracting estimated losses from measured power loss, determining the presence of foreign objects and applying appropriate mitigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional FOD systems use simple power loss thresholds, then the system is easier to operate, but measurement precision of friendly metal losses deteriorates
Solution Approach 1:
The system changes parameters by receiving multiple coefficients (α, β, γ, δ) that relate to different aspects of power transfer (current, voltage, coupling factor). These parameters are used in a comprehensive power loss estimation equation: Ploss = α·(ITX)² + β·ITX + γ·Vin + δ·Vin², where ITX is transmit coil current and Vin is inverter voltage. This multi-parameter approach improves measurement precision while maintaining ease of operation through automated calculations.
Solution Approach 2:
The system implements feedback by receiving coupling factor information from the counterpart device and using it to select appropriate coefficients for the power loss estimation. The controller continuously monitors power transfer parameters and adjusts the loss estimation based on the measured coupling factor, creating a closed-loop system that improves accuracy without increasing operational complexity.
2Measurement precision
If FOD systems account for all known parameters, then measurement precision improves, but device complexity increases
Solution Approach 1:
The system achieves universality by using a single power loss estimation equation that works across different coupling conditions and device configurations. The same equation Ploss = α·(ITX)² + β·ITX + γ·Vin + δ·Vin² is used regardless of the specific coupling factor, making the system universally applicable. The coefficients are selected based on coupling factor, but the overall approach remains unified and does not require separate complex systems for different conditions.
Solution Approach 2:
The system performs preliminary action by pre-determining the coefficients (α, β, γ, δ) for different coupling factors before actual power transfer begins. The counterpart device provides its coupling factor characteristics in advance, allowing the transmitter to select the appropriate coefficients before measuring power loss. This preliminary preparation simplifies the actual measurement process and reduces real-time computational complexity.
3Reliability
If FOD systems use conservative power reduction measures, then reliability improves, but productivity decreases
Solution Approach 1:
The system replaces conservative mechanical-style power reduction switches with a refined calculation-based approach. Instead of simply reducing power when any loss is detected, the system uses the precise power loss estimation equation to calculate the actual friendly metal losses and only triggers FOD mitigation when losses exceed the threshold. This substitution of calculation for conservative switching maintains reliability while improving productivity by avoiding unnecessary power reductions.
Solution Approach 2:
The system applies partial action by using only the necessary portion of conservative measures. Rather than always reducing power to account for uncertainty, the system calculates the actual expected losses using the coefficient-based equation and applies mitigation only when necessary (when measured losses exceed estimated losses plus threshold). This partial application of conservative measures maintains safety while minimizing impact on power transfer efficiency.
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
Improves the accuracy of friendly metal loss estimation, enabling effective foreign object detection and preventing unnecessary power reductions or interruptions, thus enhancing the efficiency and reliability of wireless power transfer.
Implementation Method 1
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.