Wireless Power Transmitter Foreign Object Detection and Interference Avoidance
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Solution Overview
Problem
Wireless power transmitters face challenges in determining whether a foreign object is present before transmitting power and in avoiding interference from communication devices, such as head units and keyfobs, which can overlap with wireless charging frequencies.
Innovation Solution
A method involving the transmission of analog and digital ping signals to detect foreign objects and modulate current flow using PWM, along with frequency band switching to avoid interference, allowing the wireless power transmitter to determine object presence and adjust frequency bands to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If wireless power transmission is performed at high power, then power transfer efficiency is improved, but the risk of foreign object heating and interference with communication devices increases
Solution Approach 1:
The system performs foreign object detection and communication interference detection before initiating high-power wireless transmission. By detecting the presence of foreign objects and measuring communication signal interference levels in advance, the system prevents harmful effects before they occur, allowing safe high-power transmission only when conditions are appropriate.
Solution Approach 2:
The system continuously monitors foreign object presence and communication signal interference during power transmission. Based on feedback from these detections, the system dynamically adjusts transmission power levels - reducing or stopping transmission when foreign objects are detected or communication interference exceeds thresholds, and maintaining or increasing power when conditions are safe.
2Reliability
If foreign object detection is performed before power transmission, then safety is improved, but transmission time is increased
Solution Approach 1:
The system performs a quick initial foreign object detection using a simplified method before transmission, and only performs more thorough detection or takes corrective actions when foreign objects are actually detected. This partial application of detection rigor minimizes time loss while maintaining safety - the system doesn't always perform maximum detection, only when necessary.
3Object-affected harmful factors
If frequency band switching is performed to avoid communication interference, then interference avoidance is improved, but system complexity is increased
Solution Approach 1:
The system changes the operating frequency parameter of the wireless power transmission system to avoid communication interference. By detecting interference levels at different frequencies and switching to a cleaner frequency band when necessary, the system reduces communication interference while adding only moderate complexity through frequency tuning capabilities.
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
Effectively detects foreign objects on the wireless power transmitter and avoids interference with communication signals, ensuring safe and efficient wireless power transfer.
Implementation Method 1
a magnetic inductive wireless power transfer has published a standard document
Implementation Method 2
the receiver receives a power signal from the transmitter in a wireless manner
Data Source
Figure 1~2b
Figure 3~4a
Figure 4b~5
AI summary
The present disclosure relates to a wireless power transfer method, a wireless power transfer apparatus, and a wireless charging system in a wireless power transfer field, and there is provided a foreign object detection method of a wireless power transmitter formed to transmit power to a wireless power receiver in a wireless manner, and the method may include acquiring the frequency characteristics of a current flowing through a coil within the wireless power transmitter for a predetermined period of time, detecting a peak frequency corresponding to a peak value using the acquired frequency characteristics, and comparing the peak frequency with a resonant frequency of the wireless power transmitter, and detecting whether or not the foreign object is placed on the transmitter through the comparison. In addition, the present disclosure relates to a wireless power transfer method, a wireless power transfer apparatus, and a wireless charging system in a wireless power transfer field, and there is provided a interference avoidance method of a wireless power transmitter formed to transmit power to a wireless power receiver in a wireless manner, and the method may include connecting a head unit of an automobile in a wireless manner through a communication device, receiving a first signal for avoiding interference from the head unit to stop wireless charging or change a first frequency band of the wireless charging to a second frequency band which is a different frequency band, and receiving a second signal from the head unit to resume the wireless charging or change the second frequency band to the first frequency band.