Common Mode Choke Coil with Parallel Resonance Circuit
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Solution Overview
Problem
Existing common mode choke coils suffer from large transmission loss due to high DC resistance values, which are incurred to form attenuation poles in wide frequency bands, leading to inefficient noise filtration.
Innovation Solution
A common mode choke coil design featuring a differential transmission line with magnetically coupled coils and a parallel resonance circuit, where the resonant frequencies of the main circuit and parallel resonance circuit are equal, reducing impedance for differential signals and increasing impedance for common mode noise, thereby minimizing transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If coils are connected in series to form attenuation poles in wide frequency bands, then common mode noise attenuation is improved, but DC resistance value increases leading to large transmission loss
Solution Approach 1:
The filter is divided into a main circuit and a parallel resonance circuit that operate at different frequency bands. The main circuit handles lower frequency common mode noise while the parallel resonance circuit targets higher frequency noise, allowing each circuit to use fewer series coils and thus reducing overall DC resistance and transmission loss.
Solution Approach 2:
The patent extends the filtering capability from a single frequency band to multiple frequency bands by adding the parallel resonance circuit. This dimensional extension in frequency domain allows achieving wide band attenuation without proportionally increasing the number of series coils in each path, thereby controlling transmission loss.
2Object-affected harmful factors
If multiple series coils are used to create attenuation poles, then noise filtration performance is improved, but the device size increases
Solution Approach 1:
The filtering function is segmented between the main circuit and parallel resonance circuit, each handling specific frequency ranges. This segmentation allows using fewer coils per circuit while achieving comprehensive wide-band noise filtration, thereby reducing the overall device volume.
Solution Approach 2:
The parallel resonance circuit serves multiple functions: it provides attenuation poles in the high frequency band, extends the overall frequency coverage of the filter, and works cooperatively with the main circuit. This multi-functionality allows achieving wide band noise suppression without proportionally increasing device size.
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 attenuates common mode noise across a wide frequency band while reducing transmission loss and allowing for miniaturization of the choke coil.
Implementation Method 1
a first coil provided in the first signal line, and a second coil provided in the second signal line and connected to the first coil by magnetic field coupling
Implementation Method 2
a third coil connected to both the first coil and the second coil by magnetic field coupling
Implementation Method 3
a first resonant frequency of the main circuit is the same or substantially the same as a second resonant frequency of the parallel resonance circuit
Data Source
AI summary
A common mode choke coil includes a differential transmission line including first and second signal lines, a main circuit including a first coil provided in the first signal line, and a second coil provided in the second signal line and connected to the first coil by magnetic field coupling, and a parallel resonance circuit including a third coil connected to both the first and second coils by magnetic field coupling, and a first capacitor electrically connected in parallel to the third coil. In the common mode choke coil, a first resonant frequency of the main circuit is equal or substantially equal to a second resonant frequency of the parallel resonance circuit.