Intermediate Resonant Coil Control for Wireless Power Leakage
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Solution Overview
Problem
Existing inductive power transfer systems face challenges in regulating high power transfer over large distances without local regulation, particularly in wireless EV charging, where increasing the primary pad's VA ratings to manage magnetic leakage fields becomes costly and inefficient, and determining the appropriate position and tuning of an intermediate resonant coil is complex.
Innovation Solution
The method involves controlling the intermediate resonant circuit by regulating the secondary coil's VA, which in turn controls the power supplied and leakage fields, using a power regulation circuit with components like DC/DC converters, bridge circuits, and switching circuits to manage the VA in the intermediate coupling structure, and determining the physical distance between coils to optimize power transfer and leakage control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the primary pad's VA ratings are increased to manage magnetic leakage fields at large air gaps, then power transfer capability is improved, but system cost and magnetic leakage fields increase
Solution Approach 1:
An intermediate resonant coil is introduced between the primary and secondary coils to act as a mediator for magnetic field coupling. This intermediate coil enables power transfer across large air gaps without requiring excessive VA ratings from the primary pad, thereby reducing magnetic leakage fields while maintaining power transfer capability.
Solution Approach 2:
The system changes operating parameters by introducing resonant frequency tuning and intermediate coupling coefficients. By adjusting the resonant frequency of the intermediate coil and optimizing coupling parameters, the system achieves efficient power transfer at large air gaps without increasing primary VA ratings, thus controlling magnetic leakage fields.
2Power
If the primary pad size is increased to improve power transfer at large air gaps, then power transfer capability is improved, but system cost and complexity increase
Solution Approach 1:
The magnetic coupling system is segmented into three separate coils (primary, intermediate, and secondary) rather than using a single large primary pad. This segmentation allows each coil to be optimized independently and reduces the overall system complexity compared to scaling up a single pad while achieving the same power transfer capability.
3Power
If an intermediate resonant coil is added to enable power transfer over large distances, then power transfer capability is improved, but device complexity and control difficulty increase
Solution Approach 1:
The system incorporates feedback mechanisms to monitor and adjust the resonant frequency and coupling parameters of the intermediate coil. This feedback control enables automatic optimization of the intermediate coil's position and tuning, reducing the complexity of manual positioning and tuning while maintaining efficient power transfer.
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 allows for efficient power transfer over larger air gaps while maintaining safe magnetic leakage levels, reducing system costs and complexity by dynamically controlling the intermediate coil's VA and leakage fields, thus enabling wireless charging of vehicles with varying ground clearances.
Implementation Method 1
the intermediate circuit is magnetically coupled
Implementation Method 2
The coils each comprise part of a magnetic structure
Implementation Method 3
Typical IPT systems use two resonant coils to couple power
Data Source
AI summary
A method and apparatus for controlling an intermediate resonant circuit in a wireless power or IPT system includes regulating a secondary with which the intermediate circuit is magnetically coupled so as to control the VA in the intermediate resonant circuit and to control magnetic leakage fields.