Wireless Charging Foreign Object Detection via Power Loss Estimation
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Solution Overview
Problem
Existing wireless charging systems face inefficiencies and safety hazards due to foreign objects heating up when they absorb power from the transmitter, leading to reduced efficiency and potential damage or fire, and current methods relying on expensive electrical current sensors are prone to failures and costs.
Innovation Solution
The system employs measurement voltage potential instead of current sensors to detect foreign objects by characterizing power loss through a characterization phase and estimating power supplied to the receive coil, allowing for reliable detection without expensive current sensing circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical current sensors are used to detect foreign objects, then detection reliability is improved, but device cost and complexity increase
Solution Approach 1:
The patent extracts the foreign object detection function from the power transmission path by measuring voltage at a point before the power inverter, rather than sensing current in the high-power transmit coil circuit. This voltage-based measurement approach eliminates the need for complex high-current sensors while maintaining detection capability.
Solution Approach 2:
The patent introduces a voltage measurement as an intermediary parameter to indirectly detect foreign objects. Instead of directly measuring current in the transmit coil, the system measures voltage at an intermediate point and uses power loss calculations to infer the presence of foreign objects, simplifying the sensing requirements.
2Measurement precision
If electrical current sensors are used to detect foreign objects, then detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, fragile current sensors with inexpensive voltage measurement circuitry. The voltage sensing approach uses standard, low-cost components that are readily available and easy to manufacture, eliminating the need for specialized high-current sensor assemblies.
Solution Approach 2:
The patent substitutes electrical current sensing with a voltage measurement-based detection method. By measuring voltage and calculating power loss through mathematical relationships rather than direct current measurement, the system achieves equivalent detection precision using simpler, cheaper electronic components.
3Device complexity
If power loss characterization is used to detect foreign objects, then device complexity is reduced, but measurement precision must be maintained
Solution Approach 1:
The patent implements a feedback mechanism where the measured voltage is used to calculate transmitted power, which is then compared against expected power levels to detect foreign objects. The system continuously monitors and adjusts based on the calculated power loss, maintaining precision through closed-loop measurement and comparison.
Solution Approach 2:
The patent performs preliminary characterization of the power loss relationship between voltage and transmitted power during system calibration. By pre-establishing the expected power transmission characteristics, the system can accurately detect deviations indicating foreign objects without requiring complex real-time analysis, thus maintaining precision with simpler hardware.
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 enables reliable detection of foreign objects using low-cost components, reducing false trips and ensuring safe operation by comparing power loss with a dynamic threshold, thus preventing overheating and potential hazards.
Implementation Method 1
a transmitter of a transmitting device may generate an electromagnetic field, and a receiver of a receiving device may extract power from the electromagnetic field
Implementation Method 2
Foreign objects in proximity to a transmit coil may, however, draw power from the transmitter and may heat up
Data Source
AI summary
Foreign object detection for wireless power transmission and related systems, methods, and devices are disclosed. A controller for a wireless power transmitter is to determine a transmit coil voltage potential at a transmit coil of the wireless power transmitter, determine an input power provided to the wireless power transmitter, determine a transmitter power loss, and determine a transmitted power of the wireless power transmitted to the wireless power receiver based, at least in part, on the input power and the transmitter power loss. The controller is also to compute a power loss responsive to the transmitted power and a received power indicated by the wireless power receiver, and determine that a foreign object is detected responsive to a determination that the power loss is greater than a predetermined threshold.