Litz-Wire Hollow Coil Packaging for High-Frequency Loss Reduction
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Solution Overview
Problem
Conventional power inductors face challenges such as high high-frequency alternating-current load loss, high winding temperature rise, low alternating-current voltage withstanding, and mechanical issues like wire breaking under pressure, due to the skin effect and adjacent effect of round or flat wires at high frequencies.
Innovation Solution
The inductive component employs a hollow coil wound with Litz wire, which is formed by twisting self-adhesive insulated wires, and is covered with a magnetic plastic packaging layer. This configuration reduces the skin effect and adjacent effect, thereby minimizing alternating current impedance and high-frequency loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If round wire or flat wire is used to wind a hollow coil, then the inductor can be manufactured with conventional methods, but high-frequency alternating-current load loss increases due to skin effect and adjacent effect
Solution Approach 1:
The patent segments the conductor into multiple thin insulated wires twisted together to form Litz wire. This segmentation reduces the skin effect and adjacent effect by distributing the current across multiple smaller conductors, thereby reducing high-frequency alternating-current load loss while maintaining electrical performance and voltage withstanding capability.
Solution Approach 2:
The patent uses composite Litz wire structure consisting of multiple insulated wires twisted together, combining the benefits of reduced skin effect with maintained electrical integrity. The composite structure of multiple thin wires with insulation layers creates a conductor that performs better at high frequencies while maintaining reliability.
2Loss of energy
If the width-to-thickness ratio of flat wire is increased to reduce skin effect, then high-frequency loss decreases, but bending force increases causing surface cracking
Solution Approach 1:
Instead of using a single wide flat wire that is difficult to bend, the patent segments the conductor into multiple thin wires. Each thin wire is easy to bend without cracking, and when twisted together they form a flexible Litz wire that reduces skin effect while maintaining bendability and mechanical strength.
Solution Approach 2:
The patent changes the geometric parameters of the conductor by using multiple thin wires instead of one wide wire. This parameter change (from wide single wire to multiple thin wires) reduces the bending radius requirements and eliminates surface cracking while maintaining or improving electrical performance at high frequencies.
3Stability of the object's composition
If cold pressing or hot pressing is used to form the inductor coil, then the coil structure is consolidated, but thin wire diameter coils are easy to break under pressure causing open circuit
Solution Approach 1:
The patent applies insulation coating to each wire before assembly, and uses the twisted Litz wire structure as a cushioning mechanism. The multiple insulated wires distribute the pressing forces, preventing any single wire from breaking under the high pressure of cold or hot pressing, thereby maintaining coil structure consolidation without wire breakage.
Solution Approach 2:
The patent uses composite Litz wire structure with multiple insulated wires that collectively withstand pressing forces. The composite structure distributes mechanical stress across multiple elements, preventing open circuits during consolidation processes while maintaining structural integrity.
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 use of Litz wire and magnetic plastic packaging in the inductive component effectively reduces alternating current impedance and high-frequency loss, while also preventing mechanical issues like wire breaking and open circuits, resulting in improved performance and reliability.
Implementation Method 1
due to the skin effect and the adjacent effect of the round wire (flat wire) at high frequency
Implementation Method 2
due to the skin effect and the adjacent effect of the round wire (flat wire) at high frequency
Implementation Method 3
a magnetic plastic packaging layer covering the coil
Data Source
AI summary
An inductive component comprises a hollow coil wound by Litz wire, a magnetic plastic packaging layer covering the coil, and a first electrode and a second electrode of the coil. The first electrode and the second electrode are exposed outside the magnetic plastic packaging layer. A manufacturing method for the inductive component comprises: winding a hollow coil by using Litz wire; connecting two leading-out terminals of the coil to portions of a leadframe to be formed into two electrodes; manufacturing a formed magnetic plastic packaging layer on the periphery of the coil; curing the magnetic plastic packaging layer through heat treatment; and carrying out leadframe cutting on the cured semi-finished product to form the two electrodes exposed outside the magnetic plastic packaging layer, and bending the two electrodes to flatly extend to the surface of the magnetic plastic packaging layer.