Inductive Charging Coil Winding Direction for Positioning Tolerance
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Solution Overview
Problem
Existing inductive charging systems require precise positioning of primary and secondary coil units for efficient power transfer, which is challenging, especially in applications like electric vehicle charging where exact alignment is difficult to achieve.
Innovation Solution
The coil arrangement modifies the winding direction of at least one coil unit to ensure that magnetic flux is constant over a larger area, allowing for more tolerant positioning by superposing magnetic fluxes generated by windings with opposite directions, and includes resonance control to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional single-direction winding arrangement is used, then the magnetic flux is concentrated at a specific position, but the positioning tolerance between primary and secondary coil units is poor
Solution Approach 1:
The coil winding is segmented into multiple independent windings with different winding directions. Instead of using a single continuous winding, the patent divides the coil into several segments (e.g., first winding, second winding, third winding) that can be independently controlled. This segmentation allows different portions of the coil to generate magnetic flux in different directions, thereby expanding the area of constant magnetic flux and improving positioning tolerance between primary and secondary coil units.
Solution Approach 2:
The patent introduces asymmetry in the winding directions of different coil segments. Specifically, adjacent windings are wound in opposite directions (e.g., first winding in clockwise direction, second winding in counter-clockwise direction). This asymmetric winding arrangement creates opposing magnetic fluxes that cancel each other out in certain regions, resulting in a broader area of relatively constant magnetic flux density, which directly improves positioning tolerance.
2Reliability
If multiple windings with opposite directions are used to flatten the magnetic flux peak, then the positioning tolerance is improved, but the device complexity increases
Solution Approach 1:
The patent merges multiple windings with opposite directions into a single integrated coil structure. Instead of treating each winding as a separate device, they are combined into one coil unit where all windings share common electrical connections (series or parallel configuration). This merging approach maintains the benefits of multiple opposing windings (improved positioning tolerance and reliability) while reducing device complexity by consolidating the structure and control circuitry.
3Ease of operation
If exact positioning is required for efficient power transfer, then the power transfer efficiency is high, but the ease of operation is reduced
Solution Approach 1:
The patent creates an equipotential-like condition in the magnetic flux distribution by using opposing windings to cancel out flux variations. The multiple windings with opposite directions generate magnetic fluxes that compensate for each other, creating a broader region where the magnetic flux density remains relatively constant. This equipotential effect in the magnetic field allows the system to maintain high power transfer efficiency over a range of positions rather than requiring exact positioning.
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 positioning tolerance and maintains high efficiency in inductive power transfer, enabling effective charging even with slight misalignment, and allows for bidirectional power transfer and data signal transmission.
Implementation Method 1
at least one of the coil windings of said primary coil unit and/or said secondary coil unit, respectively, is arranged and/or adapted such that it has a different winding direction compared to the other windings of the same coil unit, i.e. a current running through that at least one winding (having a different winding direction) runs in a different direction than the current running through the other windings of the same coil unit
Implementation Method 2
The idea behind that is that the magnetic field above such a modified coil unit is as constant as possible in an area that is as large as possible, which is achieved by the different magnetic fluxes generated by said at least one winding and the remaining windings which magnetic fluxes superpose each other
Data Source
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AI summary
The present invention relates to a coil arrangement for use in an inductive charging device, comprising a primary coil unit having a first number of primary windings arranged in a primary plane and secondary coil unit having a second number of coil windings substantially arranged in a secondary plane, wherein said primary plane and said secondary plane are arranged substantially in parallel, wherein said primary coil unit and said secondary coil unit are movable relative to each other, and wherein at least one of said primary winding has an opposite winding direction than the other primary windings and/or at least one of said secondary windings has an opposite winding direction than the other secondary windings. Further, the present invention relates to an inductive charging unit.