Wireless Power Coil Coupling Measurement for Alignment Detection
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Solution Overview
Problem
Existing wireless power transfer systems lack efficient methods for accurately determining the magnetic coupling coefficient between a wireless power transmitter and receiver, which is crucial for regulating power transfer and detecting foreign objects, often relying on complex pre-manufacture testing.
Innovation Solution
A wireless power transmitter measures circuit parameters with the receiver coil effectively short circuited and open circuited, using equations to determine magnetic and resistive coupling coefficients based on resonant frequencies and inductances, allowing in-field estimation without extensive pre-manufacture testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex pre-manufacture testing is used to determine magnetic coupling coefficient, then measurement precision is improved, but device complexity and manufacturing time increase
Solution Approach 1:
The patent replaces complex physical pre-manufacture testing with an electrical measurement method. By measuring inductance values (Lself, M) through electrical circuits and calculating the magnetic coupling coefficient k = M/√(L1·L2), the system substitutes mechanical/physical alignment testing with electrical parameter measurement, reducing manufacturing complexity while maintaining measurement precision
Solution Approach 2:
The system enables the wireless power transmitter to self-determine its magnetic coupling coefficient using built-in measurement capabilities. The controller measures inductance parameters and calculates k without requiring external testing equipment or complex pre-manufacture procedures, allowing the device to characterize its own coupling properties
2Loss of time
If in-field estimation of coupling coefficient is implemented, then manufacturing time is reduced, but measurement precision may deteriorate
Solution Approach 1:
The patent performs preliminary measurement of inductance parameters (Lself, M) during manufacturing or initialization, storing these values for later use. This preliminary electrical characterization enables rapid in-field estimation without requiring time-consuming physical testing at the point of use, achieving both time reduction and maintained precision
Solution Approach 2:
The system dynamically adjusts power transfer based on the pre-determined coupling coefficient. By having the coupling parameter k = M/√(L1·L2) available from preliminary measurements, the controller can adapt power transfer settings in real-time without requiring repeated measurement, enabling fast response while maintaining accuracy
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 accurate and efficient determination of magnetic coupling coefficients during the wireless power transfer process, improving alignment detection and foreign object detection capabilities.
Implementation Method 1
a wireless power transmitting coil that receives the AC voltage from the inverter, the wireless power transmitting coil being couplable to a wireless power receiving coil of a wireless power receiver
Implementation Method 2
an inverter that generates an AC voltage when receiving an input voltage
Data Source
AI summary
Determining an indication of coupling between a wireless power transmitting coil of a wireless power transmitter and a wireless power receiving coil of a wireless power receiver can include measuring one or more circuit parameters of the wireless power transmitter with the wireless power receiving coil effectively short circuited; measuring one or more circuit parameters of the wireless power transmitter with the wireless power receiver coil open circuited; and combining the one or more circuit parameters of the wireless power transmitter measured with the wireless power receiving coil effectively short circuited with the one or more circuit parameters of the wireless power transmitter measured with the wireless power receiver coil open circuited.