Wireless Charging Coil Temperature Sensing for Metal Object Heating
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Solution Overview
Problem
Wireless charging systems face issues with power loss and potential damage due to heat generated by metal foreign substances, which can also pose a risk to user safety, and there is a need to improve power transmission efficiency.
Innovation Solution
A wireless power transmission apparatus is designed with a temperature sensor, such as a pattern resistor or thermistor, mounted on a flexible printed circuit board, which detects heat generated by metal foreign substances, allowing for the adjustment of power transmission to prevent damage and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless power transmission is performed using a transmit coil, then power transmission efficiency is improved, but heat is generated by eddy currents in metal foreign substances causing power loss and potential damage
Solution Approach 1:
The patent performs foreign object detection before power transmission begins by measuring the impedance of the transmit coil. If metal foreign substances are detected, the system prevents power transmission or adjusts transmission parameters in advance, avoiding energy loss from heating metal objects while maintaining efficient power transfer to legitimate devices.
Solution Approach 2:
The system continuously monitors impedance changes during wireless charging and uses this feedback to detect metal foreign substances. When detection occurs, the control unit adjusts or stops power transmission to prevent energy loss, while maintaining optimal transmission efficiency when no foreign objects are present.
2Productivity
If wireless power transmission is performed using a transmit coil, then power transmission efficiency is improved, but the wireless power transmission apparatus or reception apparatus may be damaged due to heat generated by eddy currents
Solution Approach 1:
The patent performs foreign object detection before power transmission begins by measuring the impedance of the transmit coil. If metal foreign substances are detected, the system prevents power transmission or adjusts transmission parameters in advance, avoiding energy loss from heating metal objects while maintaining efficient power transfer to legitimate devices.
Solution Approach 2:
The system continuously monitors impedance changes during wireless charging and uses this feedback to detect metal foreign substances. When detection occurs, the control unit adjusts or stops power transmission to prevent energy loss, while maintaining optimal transmission efficiency when no foreign objects are present.
3Object-affected harmful factors
If a temperature sensor is mounted on the wireless power transmission apparatus to detect metal foreign substances, then user safety is improved, but device complexity increases
Solution Approach 1:
The patent replaces physical temperature sensors with an electrical impedance-based detection system. By measuring changes in the transmit coil's impedance caused by eddy currents in metal foreign substances, the system achieves foreign object detection without adding mechanical sensor components, thus maintaining user safety while avoiding increased device complexity.
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
The solution effectively detects heat from metal foreign substances, preventing power loss and damage, while improving the efficiency of wireless charging by adjusting power transmission accordingly.
Implementation Method 1
The basic principle of wireless charging is to rectify an Alternating Current (AC) current to charge the battery, when a magnetic field is formed around a transmit coil when flowing the AC current in the transmit coil
Implementation Method 2
at least one temperature sensor including a pattern resistor, a resistance numerical value of which varies with a temperature
Implementation Method 3
ground wiring connected with the at least one temperature sensor to ground the at least one temperature sensor
Data Source
AI summary
A wireless power transmission apparatus is provided. The wireless power transmission apparatus includes an upper housing, a lower housing coupled to the upper housing, a substrate disposed between the upper housing and the lower housing, a transmit coil disposed between the upper housing and the substrate and formed by being wound in the form of rotating on the substrate, at least one temperature sensor including a pattern resistor, a resistance numerical value which varies with temperature, and a flexible printed circuit board (FPCB) on which the at least one temperature sensor is disposed. The pattern resistor is disposed on the FPCB in a pattern of being wound in a first direction from any first point on the FPCB to any second point different from the any first point on the FPCB around a central portion of the FPCB and being rewound in a second direction opposite to the first direction.