Inductive Power Coil EMF Estimation for Foreign Object Detection
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Solution Overview
Problem
Existing wireless power transmission systems face challenges in accurately estimating the induced electromotive force (EMF) due to foreign objects, which can cause inefficiencies and safety concerns, and current methods require high-performance instrumentation or complex systems.
Innovation Solution
A method that monitors two variables derived from the switching waveform, such as the amplitude of harmonics and phase differences, to determine the magnetically induced voltage on a coil, allowing for accurate estimation without the need for high-performance instrumentation, and enables detection of foreign objects within the wireless power transmission range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If foreign object detection is implemented using existing methods, then detection accuracy is improved, but device complexity and instrumentation requirements increase
Solution Approach 1:
The patent extracts only the essential information needed for foreign object detection by monitoring specific variables (input current, switching waveform characteristics) rather than measuring the entire voltage waveform. This extraction approach maintains detection accuracy while significantly reducing instrumentation complexity and removing the need for high-performance measurement devices.
Solution Approach 2:
The patent uses readily available system variables (input current, switching waveform) as intermediaries to indirectly determine the induced EMF and detect foreign objects. Instead of directly measuring difficult-to-obtain parameters, the method uses these intermediary variables that are already present in the system operation, simplifying the measurement setup while maintaining detection capability.
2Measurement precision
If comprehensive voltage waveform analysis is performed, then foreign object detection accuracy is improved, but processing time and computational requirements increase
Solution Approach 1:
The method extracts only the critical features from the voltage waveform (harmonic amplitudes, phase angles) rather than analyzing the entire waveform in detail. This selective extraction maintains foreign object detection accuracy while significantly reducing the computational burden and processing time required.
Solution Approach 2:
The patent applies partial action by monitoring only two key variables instead of performing comprehensive waveform analysis. This partial monitoring approach provides sufficient information for accurate foreign object detection while minimizing processing requirements and time loss.
3Device complexity
If simple monitoring methods are used, then device complexity is reduced, but induced EMF estimation accuracy deteriorates
Solution Approach 1:
The patent uses feedback by continuously monitoring the relationship between input current and switching waveform characteristics, and using this feedback to determine the induced EMF. This feedback mechanism allows simple monitoring hardware to achieve accurate estimation by leveraging the dynamic relationship between system variables.
Solution Approach 2:
The method changes the approach from direct voltage measurement to monitoring parameter relationships (current and waveform characteristics). By focusing on how these parameters change and relate to each other during operation, the system achieves accurate induced EMF estimation using simple monitoring equipment.
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
This approach allows for cost-effective and efficient detection of foreign objects and accurate estimation of induced voltage, improving system efficiency and safety by reducing power transfer to non-intended objects and minimizing unwanted heating effects.
Implementation Method 1
an alternating current passes through a transmitter coil. This causes the transmitter coil to produce a time-varying magnetic field. When a receiver coil is placed in the time-varying magnetic field, the magnetic field induces an alternating current in the receiver coil
Implementation Method 2
monitoring a first variable associated with the wireless power transmission device; monitoring a second variable associated with the wireless power transmission device, wherein at least one of the first and the second variable is derived from a switching waveform
Data Source
AI summary
Disclosed herein are methods and systems of determining a magnetically induced voltage on a coil of a wireless power transmission device. The method comprises supplying DC input power to the wireless power transmission device. It further comprises monitoring a first variable associated with the wireless power transmission device, and monitoring a second variable associated with the wireless power transmission device, wherein at least one of the first and the second variable is derived from a switching waveform. It further comprises determining, based on at least one of the first variable, the second variable, and the relationship between the first variable and the second variable, the magnetically induced voltage on the coil of the wireless power transmission device.