Composite Magnetic Core for Reactor Saturation and Loss Balance
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Solution Overview
Problem
Magnetic cores used in reactors face challenges in achieving a balance between low-loss characteristics and high saturation magnetic flux density, with pure iron powders leading to high manufacturability issues due to small particle size and iron alloy powders resulting in low saturation magnetic flux density, while increasing the magnetic substance powder content complicates the manufacturing process.
Innovation Solution
A composite material is developed using a mixture of magnetic substance powders with different relative permeabilities, including pure iron and iron alloy powders, and coated powders, along with a specific particle size distribution and non-magnetic substance powders to enhance manufacturability and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pure iron powder is used as the magnetic substance powder, then the saturation magnetic flux density is high, but the eddy current loss increases due to small electrical resistance
Solution Approach 1:
The patent uses a composite magnetic substance powder consisting of both pure iron powder and iron alloy powder. The pure iron powder (content: 40-80 vol%) provides high saturation magnetic flux density, while the iron alloy powder (content: 20-60 vol%) with higher electrical resistance reduces eddy current loss. This composite approach allows simultaneous achievement of high saturation magnetic flux density and low eddy current loss that cannot be achieved with either material alone.
2Loss of energy
If very fine particle size pure iron powder is used, then the eddy current loss is reduced, but the workability and manufacturability deteriorate
Solution Approach 1:
The patent optimizes the particle size parameters of the magnetic substance powder to balance eddy current loss reduction and workability. The particle size is controlled within 10-100 μm, with a specific distribution where fine particles (10-30 μm) constitute 30-70% of the total. This parameter optimization ensures that the powder maintains good flowability and packability while still achieving reduced eddy current loss through adequate particle fineness.
3Quantity of substance
If the content of magnetic substance powder is increased to increase saturation magnetic flux density, then the saturation magnetic flux density improves, but the viscosity of the mixture increases and flowability becomes poor
Solution Approach 1:
The patent optimizes the content parameter of magnetic substance powder within 50-80 vol% of the composite material. This parameter range ensures high saturation magnetic flux density while maintaining adequate flowability for manufacturing. Additionally, the patent employs a bimodal particle size distribution where fine particles fill gaps between coarse particles, improving packing density and reducing the amount of binder resin needed, thereby maintaining flowability even at high magnetic powder content.
Solution Approach 2:
The patent creates different local regions with different particle size characteristics. The mixture contains both fine particles (10-30 μm) that improve flowability and fill gaps, and coarse particles (30-100 μm) that provide structural framework and high magnetic performance. This local quality differentiation allows the mixture to maintain good flowability while achieving high saturation magnetic flux density.
4Loss of energy
If iron alloy powder is used instead of pure iron powder, then the eddy current loss is reduced, but the saturation magnetic flux density decreases
Solution Approach 1:
The patent creates a composite magnetic substance powder system combining pure iron powder and iron alloy powder in specific proportions. The pure iron powder (40-80 vol%) contributes high saturation magnetic flux density (approximately 2.15 T), while the iron alloy powder (20-60 vol%) with higher electrical resistance contributes to reduced eddy current loss. The synergistic effect of this composite material achieves both high saturation magnetic flux density and low eddy current loss, overcoming the limitations of using either material alone.
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 composite material achieves a well-balanced low-loss characteristic and high saturation magnetic flux density, improving manufacturability and reducing eddy current losses, while maintaining high packing density and magnetic component proportion.
Implementation Method 1
a low-loss composite material with a high saturation magnetic flux density
Implementation Method 2
use of a pure iron powder as the raw-material magnetic substance powder provides a composite material of a high saturation magnetic flux density thanks to the high saturation magnetic flux density of the pure iron. However, use of such a pure iron may result in a composite material with a great eddy current loss because of the small electrical resistance of the pure iron.
Implementation Method 3
the loss being the iron loss (the hysteresis loss+the eddy current loss) or the like
Data Source
AI summary
A reactor 1 of the present invention includes a coil 2 and a magnetic core 3 disposed inside and outside the coil 2 to form a closed magnetic path. At least part of the magnetic core 3 is made of a composite material containing a magnetic substance powder and a resin containing the powder being dispersed therein. The magnetic substance powder contains powders respectively made of a plurality of materials differing in the relative permeability, representatively, a pure iron powder and an iron alloy powder. Thanks to provision of the magnetic core 3 made of the composite material containing magnetic substance powders made of different types of materials, the reactor 1 achieves both a high saturation magnetic flux density and a low-loss characteristic.