Wireless Power Transfer Current Sampling for Foreign Object Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wireless power transfer systems face challenges in accurately detecting power loss to identify foreign objects, requiring complex calculations and additional circuits for precise current and coil current detection.
Innovation Solution
A wireless power transfer system with a controller that performs foreign object detection by comparing the current flowing through the transmitter coil with a predetermined threshold at a specific time instant during the switching cycle, simplifying power loss calculation and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional circuits are added to detect input current and coil current for power loss detection, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential current information needed for foreign object detection by selecting a specific time instant (one-half switching cycle) for current sampling. This eliminates the need for continuous current monitoring circuits while maintaining detection accuracy, as the current at this specific moment contains sufficient information to identify foreign objects through comparison with predetermined thresholds.
Solution Approach 2:
The existing current sensing capability of the power converter is made multi-functional by using it for both power conversion control and foreign object detection. The same current sensing circuit serves dual purposes: controlling the power conversion process and providing data for foreign object identification, thereby eliminating the need for separate detection circuits.
2Measurement precision
If complex calculations are performed for power loss detection, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing predetermined current thresholds corresponding to different foreign object scenarios. During operation, the system only needs to compare the measured current at the one-half switching cycle moment against these pre-stored thresholds, eliminating complex real-time calculations and enabling rapid foreign object detection.
Solution Approach 2:
The patent changes the detection parameter from complex power loss calculations (requiring multiple measurements and computations) to a simplified current threshold comparison at a specific time instant. This parameter transformation maintains detection effectiveness while dramatically reducing computational complexity and time requirements.
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
Enables efficient and reliable foreign object detection by reducing complexity and cost in power loss detection, ensuring accurate identification of foreign objects.
Implementation Method 1
a transmitter coil configured to be magnetically coupled to a receiver coil
Data Source
AI summary
A wireless power transfer system and a control method thereof. The wireless power transfer system includes: a transmitter coil configured to be magnetically coupled to a receiver coil; a power conversion device coupled to the transmitter coil; and a controller including a one-half cycle detection block, wherein the one-half cycle detection block is configured to establish a current sensing time instant, and wherein at the current sensing time instant, a current flowing through the transmitter coil is detected and compared to a predetermined threshold to perform foreign object detection to determine whether a foreign object is coupled to the wireless power transfer system.