Composite Wound Magnetic Core for Aircraft Transformer
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Solution Overview
Problem
Aircraft transformers face challenges in achieving high volume or mass power density, low noise emission, low magnetic losses, and sufficient damping of inrush current while maintaining a compact and lightweight design, especially at low frequencies and variable frequencies ranging from 300 Hz to a few kHz.
Innovation Solution
A composite wound magnetic core configuration using two materials with different properties, where one material has low magnetostriction and high saturation magnetization, serving as a mechanical support and inrush limiter, and the other material with low magnetostriction and low magnetic losses, optimizing the transformer's performance by reducing noise and maintaining power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single material with high saturation magnetization is used to increase power density, then the transformer mass and volume are reduced, but the inrush current increases and mechanical strength decreases
Solution Approach 1:
The patent applies composite materials by combining two different magnetic materials in a single core structure: a first material with high saturation magnetization (Js ≥ 1.5 T) to provide power density, and a second material with low magnetostriction (λsat ≤ 5 ppm) to dampen inrush current and provide mechanical strength. This composite approach allows simultaneous achievement of high power density and reliable inrush current damping that cannot be obtained with a single material.
2Loss of energy
If nanocrystalline material is used to reduce magnetic losses and noise, then manufacturing cost increases and mechanical strength decreases
Solution Approach 1:
The patent applies local quality by assigning different materials to different functional regions of the core: the first material (with higher mechanical strength and lower cost) is used where structural support and inrush current damping are needed, while the second material (with low magnetostriction) is used where noise reduction and mechanical stability are critical. This localized material assignment optimizes both performance and manufacturing cost by avoiding the use of expensive nanocrystalline material throughout the entire core.
3Power
If the magnetic core section is reduced to decrease mass, then power density increases, but mechanical strength and noise resistance decrease
Solution Approach 1:
The patent uses composite materials to maintain mechanical strength in a reduced-mass core. The first material provides high saturation magnetization for power density, while the second material with low magnetostriction and high mechanical strength compensates for the reduced core section, ensuring the core can withstand electromagnetic forces and vibrations without excessive mass.
4Reliability
If a composite structure with multiple materials is used to improve performance, then manufacturing complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the magnetic core into distinct regions or layers, each made from a different material optimized for its specific function. This segmentation allows each material to be selected and processed independently according to its requirements, simplifying the overall manufacturing process compared to attempting to create a homogeneous composite with mixed properties.
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 achieves good mechanical strength, reduced manufacturing costs, and equivalent or improved power density compared to nanocrystalline solutions, while ensuring low noise and effective damping of inrush currents, thus addressing the limitations of existing transformer designs.
Implementation Method 1
a first material with high saturation magnetization (Js ≥ 1.5 T), preferably ≥ 2.0 T, and more preferably ≥ 2.2 T
Implementation Method 2
low apparent magnetostriction at saturation (typically λsat ≤ 5 ppm, preferably ≤ 3 ppm, and more preferably ≤ 1 ppm)
Implementation Method 3
a second material with low magnetostriction (λsat ≤ 5 ppm, preferably ≤ 3 ppm, and more preferably ≤ 1 ppm)
Implementation Method 4
low magnetic losses at 40 Hz, preferably less than 20 W/kg, more preferably less than 15 W/kg, and even more preferably less than 10 W/kg for a maximum induction of 1 T
Implementation Method 5
electrical transformers capable of being carried on board aircraft. Their function is the galvanic isolation between the source network and the on-board electrical and electronic systems, as well as the voltage transformation
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a basic module of a magnetic core of a wound electrical transformer. Said basic module is characterized in that it consists of a first (1, 2) and second (3, 4) winding that are placed one on top of the other and made of a first and second material, respectively. Said first material is a crystal material having a saturation magnetization (Js) greater than or equal to 1.5 T and magnetic losses less than 20 W/kg in sine waves having a frequency of 400 Hz, for maximum induction of 1 T, and said second material is a material having an apparent saturation magnetostriction (λsat) less than or equal to 5 ppm and magnetic losses less than 20 W/kg in sine waves having a frequency of 400 Hz, for maximum induction of 1 T. The cross-sections (S1, S2) of the first winding (1, 2) and cross-sections (S3, S4) of the second winding (3, 4) are such that the proportion (S1/(S1 + S3); S2/(S2 + S4)) of the first material, having a high saturation magnetization (Js), compared to the cross-section of both materials together, is between 2% and 50%, preferably between 4% and 40%. The invention also relates to a magnetic core of an electrical transformer, comprising at least one such basic module, to a method for manufacturing said magnetic core, and to a transformer comprising said magnetic core.