Common Mode Filter Drum Core Winding Pattern
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Solution Overview
Problem
Drum-core type common mode filters face challenges in achieving high noise-reduction performance and stable characteristics, particularly in reducing mode conversion characteristics, due to variations in capacitances between different turns of coils.
Innovation Solution
A common mode filter design with specific winding patterns and inter-wire distances between turns of coils, where the first and second wires have different numbers of turns in each winding area, and are wound in a bifilar or double-layer configuration to balance capacitances and reduce mode conversion characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the number of turns is increased to achieve high inductance, then inductance value is improved, but capacitance imbalance between different turns worsens and mode conversion characteristics increase
Solution Approach 1:
The coil is divided into multiple winding areas with different numbers of turns. The first winding area has a first number of turns and the second winding area has a second number of turns, creating segmented inductance sections that balance capacitance distribution while maintaining high total inductance
Solution Approach 2:
Different winding areas are assigned different turn counts to optimize local capacitance characteristics. The first wire and second wire have different turn distributions in different areas, creating localized capacitance balancing that prevents mode conversion while accumulating high inductance
2Manufacturing precision
If automatic coil winding is used to lessen variations in characteristics, then manufacturing precision is improved, but noise-reduction performance deteriorates compared to toroidal core
Solution Approach 1:
The drum core is divided into multiple winding areas where automatic winding can be precisely controlled. Each area has specific turn counts that are easily implemented by automatic winders, maintaining manufacturing precision while achieving noise-reduction performance through balanced capacitance distribution
Solution Approach 2:
The winding structure parameters (turn counts in different areas, inter-wire distances) are optimized to balance capacitances. This parameter optimization enables automatic winding to achieve both precision manufacturing and high noise-reduction performance simultaneously
3Object-affected harmful factors
If toroidal core is used to achieve high noise-reduction performance, then noise-reduction performance is improved, but manufacturing complexity increases due to manual winding requirement
Solution Approach 1:
Instead of using a toroidal core that requires manual winding, the patent inverts the approach by using a drum core with a specific segmented winding pattern that enables automatic winding. This inversion maintains noise-reduction performance while simplifying manufacturing
Solution Approach 2:
The core geometry and winding parameters are changed from toroidal to drum core with segmented areas. This parameter change enables automatic coil winding while maintaining the capacitance balancing needed for high noise-reduction performance
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 configuration effectively reduces mode conversion characteristics, achieving high inductance and stable noise-reduction performance, optimizing the common mode filter for in-vehicle Ethernet applications.
Implementation Method 1
two inductances which is provided on each of two signal lines constituting a transmission path using a differential transmission method, respectively, and magnetically coupled with each other
Data Source
AI summary
A device includes a core having a first end and a second end, and first and second wires wound around the core, each of the first and second wires having 1st to Nth turns counting from the first end to the second end, the 1st to Nth turns including an i−1th turn, an ith turn, a jth turn, and a j+1th turn, where j is greater than i. The ith turn of the first wire is closer to the first end than the ith turn of the second wire, the i−1th turn of the second wire is closer to the first end than the ith turn of the first wire, and the i−1th turn of the first wire is closer to the first end than the i−1th turn of the second wire.