Packaged Coil Assembly With Air Gaps for High-Frequency Cooling
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Solution Overview
Problem
Existing electromagnetic coils in chokes and transformers face issues such as saturation, nonlinear behavior, eddy currents, insulation problems, and inefficient cooling due to complex manufacturing processes and inadequate insulation designs, particularly in high-frequency applications like switched-mode power supplies.
Innovation Solution
The solution involves using a thermally conductive and electrically insulating holder made of diamagnetic or paramagnetic material to house a soft-magnetic element, with an enamelled wire coil wound around it, enclosed in a thermally conductive and electrically insulating cover, and potted with a potting material, while allowing only the coil ends to protrude, providing precise air gaps and improved insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air gaps are manufactured in ferromagnetic core elements to prevent saturation, then the magnetic field strength at which saturation occurs is shifted, but the manufacturing precision and complexity increase significantly
Solution Approach 1:
The core is divided into multiple core elements with individual air gaps, allowing each gap to be manufactured separately with standard precision, avoiding the need for high-precision grinding of the entire core assembly
Solution Approach 2:
Non-magnetic spacing elements (air gaps) are introduced as intermediaries between ferromagnetic core elements, preventing direct contact and saturation while maintaining the magnetic circuit functionality
2Loss of energy
If multiple smaller air gaps are provided to reduce eddy currents, then eddy current losses are reduced, but the manufacturing complexity increases
Solution Approach 1:
The core is segmented into multiple elements with distributed air gaps, effectively reducing eddy current paths while maintaining a manageable structure through modular assembly
Solution Approach 2:
Air gaps are strategically placed at specific locations where eddy currents are most problematic, providing localized energy loss reduction without requiring complex modifications throughout the entire core structure
3Reliability
If Litz wire is used to reduce Skin effect and proximity effects, then high-frequency performance is improved, but production automation becomes difficult and temperature gradients increase
Solution Approach 1:
Standard enamelled wire is used instead of expensive Litz wire, accepting the trade-off of slightly higher high-frequency losses in exchange for significantly improved manufacturability and automation capability
Solution Approach 2:
The wire structure is changed from multi-strand Litz wire to solid enamelled wire, fundamentally altering the electrical and thermal characteristics to favor automation and thermal management
4Extent of automation
If edgewise-wound coils with enamelled wire are used instead of Litz wire, then production automation is improved, but electrical insulation becomes insufficient requiring additional potting
Solution Approach 1:
Multiple insulation mechanisms are combined: enamelled wire coating, air gaps in the core, and external potting material, creating a composite insulation system that provides robust electrical isolation
Solution Approach 2:
Air gaps and potting material serve as intermediary insulating layers between the coil and surrounding components, providing electrical isolation without requiring complex insulation structures
5Reliability
If the entire choke is potted into an insulating cover for insulation, then electrical insulation is improved, but cooling efficiency deteriorates
Solution Approach 1:
Insulation is applied locally where needed (enamelled wire, air gaps at critical points) rather than universally, allowing thermal paths to remain open in high-heat-generation areas while maintaining electrical isolation
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 design simplifies manufacturing, enhances cooling, and improves electrical insulation, allowing for efficient operation in high-frequency applications with reduced risk of short circuits and improved thermal management.
Implementation Method 1
a thermally conductive and electrically insulating holder... wherein the holder is made of a first diamagnetic material or a first paramagnetic material
Implementation Method 2
Both ferromagnetic and ferrimagnetic materials typically experience saturation behaviour when magnetic fields above a certain strength are applied to them
Implementation Method 3
the holder and the coil are such that the magnetic axis of the coil passes through at least one air gap provided by the holder
Implementation Method 4
A changing, in particular alternating, current flowing through a coil of a choke, for example, creates a changing, in particular alternating, magnetic field
Implementation Method 5
a thermally conductive and electrically insulating cover... wherein the packaged electromagnetic coil assembly comprises a thermally conductive and electrically insulating potting material
Data Source
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AI summary
The invention relates to an electrical component (9'-9‴ʺ), in particular for a switchedmode power supply, comprising at least one soft-magnetic core element (11) and at least one packaged electromagnetic coil assembly (1, 1'-1‴‴), with each packaged electromagnetic coil assembly of the at least one packaged electromagnetic coil assembly comprising (i) a thermally conductive and electrically insulating holder (2) with at least one soft-magnetic element (3), wherein the at least one soft-magnetic element (3) is within the convex hull of the holder (2) and held by the holder (2), and wherein the holder (2) is made of a first diamagnetic material or a first paramagnetic material, (ii) a coil (4) formed of enamelled wire and having a magnetic axis (5) and two ends (6), wherein the wire of the coil is wound around the holder (2) with the at least one soft-magnetic element, with the coil, the holder and the at least one soft-magnetic element forming a coil assembly (2, 3, 4), wherein the holder and the coil are such that the magnetic axis of the coil passes through at least one air gap provided by the holder, and (iii) a thermally conductive and electrically insulating cover (7), which cover comprises an inner side facing an interior space surrounded by the cover and an outer side facing an exterior space, which interior space is only accessible through one opening (8) in the cover and with the coil assembly being arranged in the interior space, wherein the cover and the coil assembly are such that only the two ends of the wire of the coil protrude through the opening, wherein the cover (7) is made of a second diamagnetic material or a second paramagnetic material, and wherein the packaged electromagnetic coil assembly comprises a thermally conductive and electrically insulating potting material, with the coil assembly being potted in the interior space surrounded by the cover with the potting material, wherein each soft-magnetic core element of the at least one soft-magnetic core element is in direct contact with at least a part of the outer side of the cover of one or more of the at least one packaged electromagnetic coil assembly, and wherein each soft-magnetic core element (11) of the at least one soft-magnetic core element (11) is at most in contact with the potting material of the at least one packaged electromagnetic coil assembly (1, 1'-1""") at surfaces of the respective soft-magnetic core element (11) facing the outer side of the cover (7) of the one or more of the at least one packaged electromagnetic coil assembly (1, 1'-1""") with which the respective soft-magnetic core element (11) is in direct contact. The invention also relates to a method for manufacturing an electrical component (9'-9‴ʺ).