Inductive Power Transfer Self-Resonant Frequency Tracking
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Solution Overview
Problem
Inductive power transfer systems face limitations in efficiency and adaptability due to the need for precise coil matching and close proximity, which increases complexity and cost, and restricts the power transfer capacity.
Innovation Solution
The system includes a base unit with a first inductive element and a target unit with a second inductive element, where a control circuit monitors power transfer efficiency and adjusts the time-varying electric current to maximize efficiency by inducing self-resonant oscillations in the secondary coil, allowing for flexible positioning and orientation without precise coil matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional coil configuration methods are used to improve power transfer efficiency, then efficiency is improved, but device complexity and cost increase due to careful tuning and matching requirements
Solution Approach 1:
The patent changes the operating parameter from fixed frequency to variable frequency that tracks the self-resonant frequency of the secondary coil. This allows the system to achieve maximum power transfer efficiency without requiring precise coil matching, as the frequency adjustment compensates for variations in coil parameters and positioning
Solution Approach 2:
The system uses the self-resonant frequency of the secondary coil as the operating frequency, allowing the secondary coil to serve its dual function of power reception and frequency reference. The control circuit detects the self-resonant frequency and automatically adjusts the primary coil's operating frequency to match, eliminating the need for complex manual tuning and matching procedures
2Loss of energy
If close proximity and precise coil matching are required to maximize efficiency, then power transfer efficiency is improved, but adaptability and ease of positioning are reduced
Solution Approach 1:
The system dynamically adjusts the operating frequency in real-time to track the self-resonant frequency of the secondary coil, which changes with positioning and orientation. This dynamic adaptation allows the system to maintain high efficiency across a wide range of positions and orientations without requiring precise initial positioning or matching
Solution Approach 2:
The control circuit continuously monitors the self-resonant frequency of the secondary coil and uses this feedback to adjust the primary coil's operating frequency. This closed-loop control enables the system to automatically adapt to changes in positioning and orientation, maintaining optimal efficiency without requiring precise manual positioning
3Loss of energy
If complex coil designs with careful tuning are used to improve efficiency, then power transfer efficiency is improved, but the amount of power that can be transferred is limited
Solution Approach 1:
The system uses periodic modulation of the primary coil at the self-resonant frequency of the secondary coil to transfer power. This resonant periodic action creates strong coupling between the coils, enabling both high efficiency and high power transfer capacity simultaneously by exploiting the resonant enhancement of the magnetic field interaction
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 power transfer efficiency by adjusting the operating frequency to align with the self-resonant frequency of the secondary coil, increasing the amount of power transferred while reducing complexity and cost, and allowing for more flexible device designs.
Implementation Method 1
applying a time varying electric current to the first inductive element to produce a time varying magnetic field, the time varying magnetic field inducing an electric current in the second inductive element
Implementation Method 2
adjusting the operating frequency to align with the self-resonant frequency of the secondary coil
Data Source
AI summary
An inductive power transfer system includes a base unit comprising a first inductive element for providing input power to a second inductive element of a target unit providing output power, a positioning structure provided on at least one of the base unit and the target unit for removably positioning the second inductive element at a predetermined orientation and distance relative to the first inductive element, a switch element configured for selectively applying a time varying electric current to the first inductive element to produce a time varying magnetic field for inducing an electric current in the second inductive element, and a control circuit for monitoring one parameter indicative of an efficiency of power transfer and automatically selectively adjusting at least one characteristic of the time varying electric current responsive to the parameter to maximize an efficiency of power transfer from the base unit to the target unit.