Wireless Power Coil Alignment Feedback for Implant Charging
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Solution Overview
Problem
Patients using implantable medical devices with rechargeable power sources face challenges in aligning external and internal coils for efficient wireless charging, as existing methods lack clear indicators for optimal alignment and efficiency, potentially leading to inefficient power transfer and overheating.
Innovation Solution
An external power source system that calculates efficiency based on power transfer and determines a coupling coefficient to indicate coil alignment, using a processor to adjust driving frequency and provide audible or graphical feedback to the user, allowing for real-time alignment adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the user manually aligns the external coil with the internal coil for wireless charging, then the charging process can be performed without physical connection, but the alignment precision is insufficient leading to inefficient power transfer and potential overheating
Solution Approach 1:
The system measures the coupling coefficient between external and internal coils in real-time and provides feedback to the user through visual or audible indicators. This feedback mechanism enables the user to adjust coil alignment based on quantitative coupling information, transforming manual alignment from a guesswork process to an informed adjustment process that achieves optimal power transfer efficiency.
Solution Approach 2:
The patent replaces manual mechanical alignment judgment with an automated electromagnetic measurement system. The coupling coefficient is determined through electrical measurements of power transfer between coils, substituting the user's subjective mechanical alignment sense with objective electromagnetic field-based measurement and indication.
2Power
If the external coil operates at high current to transfer sufficient power when misaligned, then power transfer can be maintained, but the external coil overheats
Solution Approach 1:
The system performs preliminary measurement of the coupling coefficient before initiating full-power charging. By assessing the alignment quality in advance, the system can warn users to adjust coil positioning before high current flows through the external coil, preventing overheating before it occurs rather than reacting after the problem arises.
Solution Approach 2:
Real-time monitoring of coupling coefficient provides continuous feedback during charging operation. If alignment deteriorates during charging, the system can alert the user to adjust positioning, preventing the external coil from operating in a high-current, low-efficiency state that would cause overheating.
3Productivity
If the system provides real-time alignment indication to improve power transfer efficiency, then charging efficiency increases, but the device complexity increases due to additional measurement and indication components
Solution Approach 1:
The external charging device integrates multiple functions into a single system: power transfer, coupling coefficient measurement, and alignment indication. The same electromagnetic coupling mechanism used for power transfer also serves as the basis for measuring alignment quality, eliminating the need for separate measurement hardware and reducing overall system complexity.
Solution Approach 2:
The system uses its own operating parameters (power transfer characteristics between coils) to self-diagnose alignment quality. By monitoring the electrical characteristics inherent in the wireless power transfer process, the system generates alignment information without requiring external measurement devices, making the system self-sufficient and reducing 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 system effectively indicates coil alignment through audible or graphical feedback, optimizing power transfer efficiency and preventing overheating by ensuring precise alignment of external and internal coils, thereby extending device operational life and user convenience.
Implementation Method 1
An electrical current applied to the primary coil 16 generates a magnetic field, and when the external coil 16 is aligned to the internal coil 18, the magnetic field induces an electrical current in the internal coil 18 within the patient
Implementation Method 2
a driving frequency applied to the external charging coil is adjusted to track the natural resonance frequency of the system. As the coupling coefficient increases between the two coils, the natural resonance frequency of the system will increase
Data Source
AI summary
An external power source, implantable medical device, and method for indicating an extent of power transfer between an external coil to an internal coil associated with the implantable medical device. According to one aspect, a method includes determining a parameter that depends on an extent to which the external coil is aligned with the internal coil, where the parameter includes at least one of an indication of an internal coil output power and power transfer efficiency and a resonant frequency of the external coil when inductively coupled to the internal coil. The method further includes indicating an extent to which the external coil is aligned with the internal coil based on the parameter.