Common Mode Filter Winding Segmentation Reduces Mode Conversion
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Solution Overview
Problem
Existing common mode filters exhibit high mode conversion characteristics, resulting in a significant conversion of differential mode signals to common mode signals, which limits their noise reduction performance.
Innovation Solution
A common mode filter design featuring a core-cylinder with specific winding configurations and turn counts for both coils, including an isolation region, to minimize parasitic capacitance and optimize winding arrangements, ensuring equal turns on each winding area and interleaved winding patterns to reduce mode conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional common mode filter with two coils wound around an iron core is used, then common mode noise filtering is achieved, but differential mode signal converts to common mode signal resulting in high mode conversion characteristics
Solution Approach 1:
The core-cylinder is divided into three distinct winding areas (first, second, and third winding areas), with each area containing specific portions of the coils. This segmentation allows differential mode signals to be canceled through opposite polarity windings while maintaining common mode rejection, thereby reducing mode conversion characteristics.
Solution Approach 2:
The patent introduces an isolation region in the second winding area of the second coil, creating an asymmetric winding structure. Additionally, the coils are designed with different winding directions in different areas (some wound in opposite directions), which breaks the symmetry that would otherwise cause differential mode to common mode conversion.
2Reliability
If the number of turns in the coils is increased to improve filtering performance, then common mode impedance increases, but the complexity of winding configuration increases
Solution Approach 1:
The total number of turns is distributed across three winding areas rather than concentrated in a single area. This segmentation allows the filter to achieve high common mode impedance through cumulative turns while maintaining manageable winding complexity in each individual area.
Solution Approach 2:
Different portions of the coils have different winding directions and configurations tailored to their specific functions. The first and third winding areas use one configuration while the second winding area introduces isolation regions and opposite polarity windings, optimizing local characteristics for overall 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
The design effectively reduces mode conversion characteristics and enhances noise reduction performance, improving practicality and product yield while maintaining manufacturing efficiency.
Implementation Method 1
when a noise current such as a common mode current passes through the common mode filter, the common mode current generates a magnetic field in the same direction on the first coil and the second coil; thereby increasing the inductive reactance of the first coil and the second coil
Implementation Method 2
the fifth winding portion of the second winding area is set with an isolation region between two winding turns
Data Source
AI summary
A common mode filter for reducing differential mode signal converting to common mode signal comprising: a core-cylinder, a first coil, and a second coil; wherein two ends of the core-cylinder respectively extend and set with a first flange and a second flange; wherein m1, m2, and m3 turns and n1, n2, and n3 turns are respectively and sequentially wound and set on the first winding portion, the second winding portion, and the third winding portion of the first winding area, the second winding area, and the third winding area of the first coil and the second coil. Therefore, the present invention can effectively reduce the mode conversion characteristic (Scd), and can also improve the noise reduction performance of the product; thereby greatly upgrading the practicality of the present invention; and the present invention has a simple process, therefore the product yield can be further upgraded to achieve the effect.