Inductive Power Transfer Loss Accounting for Parasitic Metal Detection
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Solution Overview
Problem
Contactless power supply systems face inefficiencies and safety concerns due to parasitic metal detection inaccuracies, leading to false positives and system restrictions, as existing methods fail to distinguish between losses from misalignment and parasitic metal effectively.
Innovation Solution
A contactless power supply system that synchronizes primary and secondary measurements to accurately detect parasitic metal by accounting for changes in known power losses, using a prediction function to differentiate between coupling losses and parasitic metal-induced losses, allowing for more precise detection and reduced false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power consumption detection is used to detect parasitic metal, then parasitic metal detection capability is provided, but false positives occur due to inability to distinguish between misalignment losses and parasitic metal losses
Solution Approach 1:
The patent segments the total power loss into multiple distinct components: misalignment loss (determined through calibration at different positions), parasitic metal loss, and normal operating loss. By measuring total loss and subtracting the calibrated misalignment component, the system isolates the parasitic metal loss for accurate detection.
Solution Approach 2:
The system changes the operational parameter of coil position to establish a calibration curve that relates position to power loss. This calibration data is then used to determine and subtract the misalignment loss component from total loss measurements, enabling accurate parasitic metal detection regardless of positioning variations.
2Ease of operation
If simple power consumption threshold detection is used, then detection simplicity is maintained, but system restrictions occur due to insufficient resolution to distinguish true positives
Solution Approach 1:
The system implements feedback by continuously monitoring power consumption and comparing it against dynamically calculated thresholds that account for misalignment losses. The calibration data provides feedback on normal loss variations due to positioning, enabling the system to distinguish true parasitic metal detections from false positives caused by misalignment.
3Measurement precision
If accounting for multiple loss components is implemented, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary calibration actions during manufacturing or initial setup, measuring power consumption at various coil positions to establish misalignment loss characteristics. This pre-determined calibration data is stored and automatically applied during operation, eliminating the need for real-time complex calculations and reducing operational system complexity while maintaining high measurement precision.
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 achieves improved accuracy in parasitic metal detection, reducing false positives and enabling timely and accurate identification of true positives, thereby enhancing the reliability and safety of contactless power transfer.
Implementation Method 1
an inductive power supply or primary unit having at least one primary coil, through which it drives an alternating current, creating a time-varying electromagnetic field
Implementation Method 2
a portable electronic device or secondary device, separable from the primary unit, including a secondary coil, which when placed in proximity to the time-varying field, the field induces an alternating current in the secondary coil
Implementation Method 3
Metal placed in the field is sometimes referred to as parasitic metal
Implementation Method 4
Metal placed in the field is sometimes referred to as parasitic metal
Data Source
AI summary
A system and method of controlling inductive power transfer in an inductive power transfer system and a method for designing an inductive power transfer system with power accounting. The method of controlling inductive power transfer including measuring a characteristic of input power, a characteristic of power in the tank circuit, and receiving information from a secondary device. Estimating power consumption based on the measured characteristic of tank circuit power and received information and comparing the measured characteristic of input power, the information from the secondary device, and the estimated power consumption to determine there is an unacceptable power loss. The method for designing an inductive power transfer system with power accounting including changing the distance between a primary side and a secondary side and changing a load of the secondary side. For each distance between the primary side and the secondary side and for each load, measuring a circuit parameter on the primary side in the tank circuit and a circuit parameter on the secondary side during the transfer of contactless energy. The method further including selecting a formula to describe power consumption in the system during the transfer of contactless energy based on coefficients and the circuit parameters, and determining the coefficients using the measured circuit parameters.