Wireless Power Coil Circuit for Sensorless Foreign Object Detection
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Solution Overview
Problem
Existing wireless power transfer systems face challenges in accurately detecting foreign objects using current sensor-based methods, which are costly and sensitive to vibration, leading to potential overheating hazards and inaccurate power loss estimation.
Innovation Solution
The system employs coil and capacitor voltage potential measurements to estimate power loss without the need for current sensors, using differential amplifiers to derive coil current and compute active power, enabling reliable foreign object detection with low-cost hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensor-based methods are used for foreign object detection, then detection capability is provided, but system cost increases and vibration sensitivity causes inaccurate power loss estimation
Solution Approach 1:
The patent extracts the foreign object detection functionality from the current sensing domain and relocates it to the voltage measurement domain. By removing current sensors and using only voltage measurements across the capacitor and coil, the system achieves foreign object detection without the complexity and cost of current sensing hardware, while avoiding vibration-related measurement errors.
Solution Approach 2:
The patent substitutes the mechanical/electrical current sensing approach with an electrical voltage measurement approach. Instead of using current sensors that require physical contact and are sensitive to vibration, the system uses voltage measurements combined with mathematical computation to derive the same detection information, replacing a problematic physical measurement method with a more robust electrical measurement method.
2Loss of energy
If current sensors are used to estimate power loss, then power loss measurement is enabled, but the system becomes sensitive to vibration and requires costly hardware
Solution Approach 1:
The patent extracts power loss estimation from the current measurement domain and implements it in the voltage measurement domain. By taking out the dependency on current sensors and using only voltage measurements across the capacitor and coil combined with computational methods, the system achieves reliable power loss estimation that is not affected by vibration.
Solution Approach 2:
The patent substitutes the vibration-sensitive current measurement method with a vibration-resistant voltage measurement method. The electrical measurement of voltage combined with mathematical computation replaces the mechanical current sensing approach, providing stable and reliable power loss estimation even under vibrational conditions.
3Device complexity
If voltage potential measurements are used instead of current sensors, then hardware cost is reduced, but accurate coil current derivation must be achieved through computational methods
Solution Approach 1:
The patent substitutes direct current measurement with computational current derivation. Instead of using current sensors to directly measure coil current, the system measures voltage across the capacitor and coil and uses mathematical computation to derive the current, replacing a hardware-intensive approach with a computation-based approach.
Solution Approach 2:
The patent changes the measurement parameter from current to voltage and uses computational transformation to recover the current information. By measuring voltage potentials and applying mathematical relationships based on the known circuit topology and component values, the system derives accurate current values without directly measuring them.
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 provides accurate and reliable foreign object detection across various conditions, reducing the need for calibration and costly hardware, while ensuring safe power transfer by preventing overheating.
Implementation Method 1
one or more inductive coils to wirelessly couple with another inductive coil
Data Source
AI summary
Foreign object detection and related apparatuses, methods, and systems are disclosed. An apparatus includes one or more inductive coils to wirelessly couple with another inductive coil, a series capacitor electrically connected in series with the one or more inductive coils, and a controller to determine a coil current through the one or more inductive coils responsive to a capacitor voltage potential difference across the series capacitor and determine a coil power responsive to the determined coil current and a coil voltage potential difference across the one or more inductive coils.