Wireless Power Coil Q-Factor Sensing for Foreign Object Detection
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Solution Overview
Problem
Wireless charging systems face challenges in accurately distinguishing between foreign objects and wireless power receiving devices, leading to potential overheating and inefficiencies due to the lack of effective detection methods.
Innovation Solution
The implementation of quality-factor measurements using impulse responses and impedance analysis to differentiate between foreign objects and wireless power receiving devices, with compensation for aging and temperature effects, allowing for precise detection and adaptive power transmission control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If quality-factor measurements are used to detect foreign objects, then detection precision is improved, but device complexity increases due to additional measurement circuitry and compensation mechanisms
Solution Approach 1:
The wireless power transmitting coil serves dual functions: it acts as both the power transmission element and the sensing element for foreign object detection. By measuring the quality factor of the transmitting coil, the system can detect foreign objects without requiring separate dedicated sensing coils or detection hardware, thereby improving detection precision while minimizing additional device complexity
Solution Approach 2:
The system uses its own transmitting coil to perform self-diagnosis for foreign object detection. The quality factor measurements are taken from the transmitting coil itself, and the system automatically compensates for temperature and aging effects using built-in sensors and algorithms, eliminating the need for external calibration devices or manual adjustments
2Reliability
If foreign object detection is implemented to prevent overheating, then safety is improved, but productivity decreases due to additional detection steps and potential power transmission interruptions
Solution Approach 1:
The system performs quality factor measurements and foreign object detection before initiating power transmission. By detecting foreign objects in advance and compensating for environmental factors beforehand, the system can prevent unsafe power transmission without requiring continuous interruptions during charging, thus maintaining productivity while ensuring safety
Solution Approach 2:
The system continuously monitors the quality factor of the transmitting coil during operation and compares it against baseline values. When changes indicate the presence of a foreign object, the system provides feedback to adjust or terminate power transmission, ensuring safety while minimizing unnecessary interruptions to normal charging operations
3Measurement precision
If compensation for aging and temperature effects is applied, then measurement precision is improved, but device complexity increases due to additional sensors and compensation algorithms
Solution Approach 1:
The system uses built-in temperature sensors and frequency counters already present in the wireless power transmitter to automatically compensate for environmental effects on quality factor measurements. The microcontroller processes these readings and applies compensation algorithms, enabling the system to maintain measurement precision without requiring external calibration equipment or manual intervention
Solution Approach 2:
The system dynamically adjusts the quality factor baseline based on measured temperature and frequency variations. By changing the reference parameters according to environmental conditions, the system compensates for aging and temperature effects on the coil's electrical characteristics, maintaining detection accuracy without adding complex 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, preventing overheating and ensuring safe and efficient wireless power transfer by distinguishing between foreign objects and intended devices, thereby optimizing power delivery.
Implementation Method 1
a wireless power transmitting device such as a charging mat wirelessly transmits power to a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device.
Implementation Method 2
The coil of the wireless power receiving device receives alternating-current wireless power signals from the wireless power transmitting device.
Implementation Method 3
The rectifier circuitry converts the received signals into direct-current power.
Data Source
AI summary
A wireless power system has a wireless power transmitting device and a wireless power receiving device. The wireless power transmitting device uses a wireless power transmitting coil to transmit wireless power signals to the wireless power receiving device. The wireless power transmitting device determines whether an external object is present. The external object may be a foreign object such as a coin or paperclip or may be a wireless power receiving device. External objects are detected using quality-factor measurements. Wireless communications are used to discriminate between foreign objects and wireless power receiving devices. Quality factor measurements may be compensated for aging and temperature effects using temperature measurements and compensation factors based on frequency and measured resistance.