EMC Filtering Device with Integrated PCB Capacitor and Inductor
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Solution Overview
Problem
Existing EMC filtering devices for printed circuit boards are inefficient in reducing conducted and radiated emissions below 100 MHz due to parasitic elements, are bulky, and costly, with known solutions either failing to limit inductance in series with capacitors or being unreliable.
Innovation Solution
An EMC filtering device with a printed circuit structure featuring high permittivity layers, ferrite core, and coupled coils positioned on either side of insulating layers, which reduces parasitic inductance and capacitance, allowing for effective filtering across high frequency ranges while being cost-effective and reliable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete filtering elements are used to reduce emissions between 10 MHz and 100 MHz, then the filtering performance is improved, but parasitic inductance is created in series with the capacitors
Solution Approach 1:
The patent merges the capacitor and inductor into a single integrated printed circuit board structure. The capacitor is formed by conductive tracks separated by a dielectric film, while the inductor is formed by spiral conductive tracks on the same board. This integration eliminates the need for discrete filtering elements and their associated parasitic inductance, as the entire filtering circuit is embedded in the PCB structure itself.
Solution Approach 2:
The patent transitions from discrete three-dimensional components to a two-dimensional planar structure on the printed circuit board. The capacitor and inductor are both formed as flat conductive patterns on the PCB surface, with the capacitor using parallel track segments separated by dielectric material and the inductor using spiral track patterns. This dimensional change reduces parasitic inductance by eliminating vertical connections and long lead paths associated with discrete components.
2Volume of moving object
If filtering devices are integrated into printed circuits, then volume is reduced, but inductance in series with capacitors cannot be limited
Solution Approach 1:
The patent combines the capacitor and inductor functions into a single integrated PCB structure. The capacitor is formed by conductive tracks with a dielectric film between them, and the inductor is formed by spiral conductive tracks on the same board. This merging eliminates the need for separate discrete components and their associated series inductance, achieving both volume reduction and parasitic inductance limitation simultaneously.
Solution Approach 2:
The patent creates a planar copy of traditional three-dimensional filtering components by representing the capacitor and inductor as two-dimensional conductive patterns on the PCB. The capacitor is copied as parallel track segments with dielectric material, and the inductor is copied as spiral track patterns, maintaining the electrical function while eliminating the physical form that generates parasitic inductance.
3Reliability
If known filtering devices are used to reduce emissions below 100 MHz, then filtering effectiveness is improved, but the devices are bulky and costly
Solution Approach 1:
The patent merges multiple filtering functions into a single integrated PCB structure that eliminates the need for bulky external filtering devices. The capacitor and inductor are both formed as conductive patterns on the same board, creating a compact filtering solution that maintains effectiveness below 100 MHz while dramatically reducing volume compared to discrete component implementations.
Solution Approach 2:
The printed circuit board serves multiple functions simultaneously: it provides the mechanical support structure, the electrical connections, and the filtering functionality. The conductive tracks serve both as signal paths and as the active filtering elements (capacitor and inductor), eliminating the need for separate filtering devices and reducing overall system volume and cost.
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 solution effectively filters out common and differential mode interference across the entire frequency range below 100 MHz, meeting stringent standards like DO160, while being easy to manufacture and reducing volume, thus enhancing the reliability and efficiency of power electronics.
Implementation Method 1
a capacitor formed by two copper electrodes separated by a dielectric film with a thickness of between 8 micrometers and 32 micrometers
Implementation Method 2
The capacitance of the capacitor depends on the permittivity and the thickness of the dielectric film
Implementation Method 3
a core made of magnetic material comprising three cylindrical arms crossing the layers perpendicularly
Implementation Method 4
coils winding around a first arm of the core made of magnetic material and a coil winding around the second arm of the core
Implementation Method 5
two coupled coils each comprising a primary winding and a secondary winding
Data Source
Figure 1a~2b
Figure 3~4
Figure 5~6a
AI summary
The invention essentially relates to an EMC filtering device (1), characterized in that said filtering device comprises a printed circuit (5) comprising at least two parallel layers (25, 26) of a high-permittivity material, which are positioned between two layers (20-22) of an insulating material that are parallel to one another and to the layers (25, 26) of a high-permittivity material, a core (10) made of a magnetic material comprising three cylindrical arms (13-15) passing perpendicularly through the layers (20-22, 25, 26), at least two windings (35, 36) winding around the first arm (13) of the magnetic material core (10), said windings (35, 36) and the first arm (13) forming a first coil (30), at least two windings (37, 38) winding around the second arm (15) of the magnetic material core (10), said windings (37, 38) and the second arm (15) forming a second coil (31), the two coils (30, 31) being coupled coils (30, 31).