Common Mode Filter Winding Blocks for Even Wire Crossings
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Solution Overview
Problem
Common mode filters with crossing wires suffer from deteriorated high-frequency characteristics due to positional relationship inversion and asymmetry, leading to issues with reflection characteristics and noise conversion.
Innovation Solution
A common mode filter design featuring a winding core with first and second wires wound in the same direction, forming specific winding blocks with odd and even turns, ensuring the wires cross each other an even number of times between blocks, maintaining symmetry and positional consistency, thereby enhancing high-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pair of wires are made to cross each other on the way to enhance symmetry between differential signals, then high-frequency characteristics are improved, but the positional relationship between the wires is inverted requiring a second crossing which causes asymmetry at wire end portions
Solution Approach 1:
The winding structure is divided into multiple winding blocks with different numbers of turns. The first and second wires are wound in opposite directions in different blocks, creating multiple crossing points. This segmentation allows the wires to cross an even number of times, restoring the original positional relationship at the wire ends while maintaining symmetry throughout the winding structure.
2Device complexity
If the wires cross each other at one end portion but not at the other end portion, then the structure is simplified, but reflection characteristics and noise conversion characteristics deteriorate
Solution Approach 1:
The patent intentionally introduces asymmetry in the winding block configuration - the first winding block has a different number of turns than the second winding block. This asymmetric design ensures that the wires cross an odd number of times in each block, resulting in an even total number of crossings. This restores symmetry at the wire ends while maintaining controlled asymmetry in the intermediate sections, optimizing both high-frequency characteristics and structural feasibility.
3Reliability
If the number of turns in the first and second winding blocks are made equal, then symmetry between winding blocks is enhanced eliminating product directionality, but the total winding length increases
Solution Approach 1:
Different winding blocks are assigned different numbers of turns based on their specific functional requirements. The first winding block has a different number of turns than the second winding block, allowing each block to be optimized locally. This local quality approach maintains the necessary asymmetry for proper wire crossing while avoiding unnecessary increase in total winding length that would result from making all blocks equal.
Data Source
AI summary
Disclosed herein is a common mode filter that includes a winding core part and first and second wires wound in a same direction around the winding core part. The first and second wires constitute a first winding block on one endmost side in an axial direction of the winding core part, a second winding block on other endmost side in the axial direction of the winding core part, and a third winding block positioned between the first and second winding blocks. The second winding block is a winding block at an odd-numbered position counted from the first winding block. The first and second wires cross each other in an area between the first and third winding blocks and in an area between the second and third winding blocks.