Toroidal Electromagnetic Filter With Nested Coils and Thermal Isolation
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Solution Overview
Problem
Existing electromagnetic filters struggle to provide high compactness and effective thermal management while operating in both common and differential modes, with limited leakage inductance and differential mode attenuation.
Innovation Solution
A toroidal-like magnetic core with separated coils and a thermal conductive magnetic compound encapsulation, along with a capacitor and sheets for thermal isolation, enhances leakage inductance and thermal link to a customer cooling plate, enabling operation in both common and differential modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional electromagnetic filter structure is used, then the filter can operate in common and differential modes, but the leakage inductance is limited and thermal management is insufficient
Solution Approach 1:
The patent merges the common mode and differential mode filter functions into a single integrated structure. The first and second coils are wound on the same toroidal magnetic core, allowing both filtering modes to be achieved without separate filter units. The thermal conductive compound also simultaneously provides both thermal management and magnetic field containment functions.
Solution Approach 2:
The patent uses a thermal conductive magnetic compound that combines thermal conductivity and magnetic properties. This composite material serves dual purposes: it conducts heat away from the coils for thermal management while also containing the magnetic field generated by the third coil, increasing leakage inductance and improving filter performance.
2Reliability
If multiple separate coils and magnetic cores are used for common and differential mode filtering, then filtering performance is improved, but compactness and thermal management are compromised
Solution Approach 1:
The patent places the capacitor and thermal isolation sheets inside the inner hollow part of the toroidal magnetic core, effectively nesting components within the magnetic structure. The third coil surrounds the entire assembly including the magnetic core and other coils, creating a nested configuration that maximizes space utilization and achieves compactness.
Solution Approach 2:
The patent combines multiple filtering functions into a single toroidal magnetic core structure. Both common mode coils (first and second coils) and the differential mode coil (third coil) are integrated around the same magnetic core, eliminating the need for separate magnetic cores and reducing overall filter volume.
3Reliability
If thermal isolation between capacitor and coils is implemented, then component protection is improved, but thermal link to cooling plate is reduced
Solution Approach 1:
The patent applies different thermal management strategies to different components. The capacitor is thermally isolated from the coils using insulating sheets to protect it from excessive heat. Meanwhile, the coils are in direct contact with the thermal conductive magnetic compound that provides a thermal path to the cooling plate, ensuring they receive adequate cooling.
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 proposed filter achieves enhanced leakage inductance and differential mode attenuation of over 20 dB @100 k-1 MHz, with improved mechanical interfaces and thermal management, meeting AEC-Q200 standards.
Implementation Method 1
a layer of a thermal conductive magnetic compound configured to enclose/encapsulate the toroidal-like magnetic core, the first, second and third coils, the capacitor, and the two sheets to: increase leakage inductance, to enclose/encapsulate the magnetic field generated by the third coil, and also to provide good thermal link to the customer cooling plate
Implementation Method 2
two sheets arranged between opposite external faces of the capacitor to thermally isolate the capacitor from the first and second separated coils
Implementation Method 3
a toroidal-like magnetic core and first and second separated coils that are wound around the toroidal-like magnetic core, the first and second separated coils and the toroidal-like magnetic core being configured to provide a common mode filter
Implementation Method 4
a third coil that is arranged to surround the toroidal-like magnetic core and the first and second separated coils and arranged around a Z axis that is coaxial with an inner hollow part of the toroidal-like magnetic core, the third coil being configured to provide a filter operating in differential mode
Data Source
AI summary
An electromagnetic filter for operating in common and differential mode having a toroidal-like magnetic core; first and second separated coils wound around the magnetic core, the first and second coils and the magnetic core configured to provide a common mode filter. The filter also has a third coil that surrounds the magnetic core and the first and second coils and arranged around a Z axis that is coaxial with an inner hollow part of the magnetic core, the third coil being configured to provide a filter operating in differential mode. Two sheets are also arranged between opposite external faces of a capacitor to thermally isolate the capacitor from the coils, the capacitor and sheets being arranged inside the inner hollow part. A layer of a thermal conductive magnetic compound encloses all the elements to increase leakage inductance and to enclose a magnetic field generated by the third coil.