Composite Magnetic Material for High-Frequency Eddy Current Loss Reduction
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Solution Overview
Problem
Magnetic elements face increased eddy current loss and corrosion issues due to high driving frequencies and exposure to air, leading to degradation of electrical characteristics, particularly in smaller size particles.
Innovation Solution
A composite magnetic material comprising Mn, Si, Cr, and Fe with specific weight ratios and a binder, where the magnetic powder has a controlled major/minor axis ratio and average particle size, and an epoxy resin is used to enhance insulation resistivity, breakdown electrical field, and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the driving frequency of magnetic elements is increased to satisfy high frequency current requirements, then the performance of electronic apparatuses is improved, but the eddy current loss in the cores increases
Solution Approach 1:
The patent changes the chemical composition parameters of the magnetic powder by adding specific amounts of Mn (0.25-3 wt%) and Cr (2-8 wt%) to Fe-Si base alloy. This compositional parameter change modifies the electrical resistivity and magnetic properties of the core material, enabling it to operate at high frequencies with reduced eddy current losses.
Solution Approach 2:
The patent creates a composite magnetic material system consisting of Fe-Si-Cr-Mn alloy powder combined with a binder resin. This composite structure allows the magnetic powder particles to be held in a dust-like state with controlled packing, reducing eddy current paths while maintaining magnetic performance for high frequency operation.
2Ease of manufacture
If alloy powder without Cr is used to reduce cost, then manufacturing cost is decreased, but the alloy powder is oxidized and rusted when exposed to air, causing alteration or deterioration of the binder and increasing core loss
Solution Approach 1:
The patent modifies the chemical composition parameters by adding Cr in the specific range of 2-8 wt% to the Fe-Si alloy. This compositional change creates a protective effect against oxidation and corrosion while the powder is exposed to air during storage and processing, preventing rust formation that would otherwise deteriorate the binder and increase core loss.
Solution Approach 2:
The patent uses a small amount of Cr (2-8 wt%, which is relatively small compared to conventional Cr contents greater than 8 wt%) to provide corrosion protection. This limited addition of Cr suffices to prevent oxidation and rust formation during the service life of the magnetic element, providing economical corrosion protection without excessive material cost.
3Loss of energy
If the size of magnetic particles is reduced to decrease core loss, then eddy current loss is decreased, but the tendency of oxidation and rust formation becomes more obvious
Solution Approach 1:
The patent changes the compositional parameters of the magnetic powder by adding Mn (0.25-3 wt%) and Cr (2-8 wt%) to the Fe-Si alloy. This compositional modification increases the oxidation resistance of the powder particles, allowing them to be produced in smaller sizes with reduced core loss while maintaining stability against oxidation and rust formation even when exposed to air.
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 magnetic material achieves low core loss, high insulation resistivity, and excellent corrosion resistance, maintaining stable electrical characteristics and reducing rust formation, thus enabling high-performance magnetic elements for electronic devices.
Implementation Method 1
joule loss (also referred to as 'eddy current loss' or 'core loss') due to eddy current increases in the cores of the magnetic elements
Implementation Method 2
the alloy powder is oxidized and rusted, when the ally powder without Cr is exposed to the air for a long period of time
Data Source
AI summary
The object of the present invention is to provide a composite magnetic material having well-balanced magnetic properties and chemical properties, and a magnetic element using thereof. Concretely, the present provides the composite magnetic material comprising a binder and a magnetic powder contains followings: Mn not less than 0.25 wt % and not larger than 3 wt %, Si not less than 1 wt % and not larger than 7 wt %, Cr not less than 2 wt % and not larger than 8 wt %, and the rest of Fe and inevitable impurities with respect to the total weight of a magnetic powder material, and a ratio of powder particles having the major/minor axis is not less than 2 is not larger than 5% of the total powder particles.