Wireless Power Coil Object Detection via Phase Monitoring
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Solution Overview
Problem
Existing wireless power transmission systems using inductive coupling are inefficient due to the inefficiency in detecting object presence within the magnetic field, leading to unnecessary energy wastage and prolonged handshake times between the transmitter and receiver.
Innovation Solution
Implementing a system that drives a primary coil with an injected signal at a substantially constant frequency to create a magnetic field and uses a controller to monitor the response, allowing for the detection of object presence by examining the steady-state condition and phase changes in the feedback signal, reducing the duration and energy expenditure of the detection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If inductive coupling is used for wireless power transmission, then power can be transferred wirelessly to portable devices, but energy efficiency deteriorates due to magnetic field loss over distance
Solution Approach 1:
The magnetic field serves dual purposes: both power transmission and object detection. By monitoring the magnetic field characteristics during the power transmission process, the system can detect the presence and position of objects without requiring separate detection mechanisms, thereby improving overall system efficiency
Solution Approach 2:
The system continuously monitors the magnetic field response to detect changes caused by nearby objects. This feedback mechanism allows the transmitter to adjust its operation in real-time, optimizing energy transfer efficiency by identifying when objects are within the magnetic field and adjusting power delivery accordingly
2Area of stationary object
If the magnetic field range is extended to cover more area, then coverage is improved, but energy efficiency deteriorates due to increased distance from primary coil
Solution Approach 1:
The system uses periodic monitoring of the magnetic field at different positions and time intervals. By pulsing the detection signal and analyzing the response at specific moments, the system can determine object presence throughout the extended coverage area without continuously transmitting high-power signals, thus maintaining energy efficiency
Solution Approach 2:
The system performs preliminary detection by monitoring magnetic field characteristics before initiating full power transmission. This preliminary action identifies the presence and position of objects in advance, allowing the system to activate power transmission only when and where needed, reducing energy waste in areas without objects
3Measurement precision
If continuous monitoring of magnetic field is performed, then object detection accuracy is improved, but energy consumption increases
Solution Approach 1:
Instead of continuous monitoring, the system performs periodic sampling of the magnetic field at strategically chosen time intervals. By analyzing the magnetic field response during specific phases of the power transmission cycle, the system achieves accurate object detection while minimizing the time and energy spent on monitoring
Solution Approach 2:
The system uses the magnetic field already being generated for power transmission as the detection medium. By monitoring the characteristics of this existing field rather than generating a separate detection field, the system achieves accurate object detection without additional energy expenditure for dedicated detection
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 enhances the detection of object presence, reducing the time and energy required for handshake processes, improving efficiency and minimizing unnecessary energy transmission, and allowing for precise identification of objects in the magnetic field.
Implementation Method 1
A primary coil driven by an injected signal at a substantially constant frequency to create a magnetic field
Implementation Method 2
a controller configured to monitor a response to the injected signal and to determine a change in a presence of an object in the magnetic field emitted from the primary coil, the determination based on the monitored response
Data Source
AI summary
The systems and methods of detecting a change in object presence in a magnetic field disclosed herein inject a low amplitude signal near the resonant frequency into the coil until the system comes to equilibrium. At this point the feedback is measured. The feedback signal can be measured as at least one of several signals, for example, but not limited to the voltage on the resonant capacitor, the current in the coil, and the voltage between the resonant capacitor and the coil. A change in the steady state response indicates a change in device presence.