Multilayer Electrical Steel Sheet Si Gradient
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Solution Overview
Problem
Conventional gradient Si magnetic materials used in high-frequency applications have high hysteresis loss, leading to insufficient reduction in iron loss, despite efforts to achieve low high-frequency iron loss and high magnetic flux density.
Innovation Solution
A multilayer electrical steel sheet with surface layers and an inner layer, where the Si concentration difference and the addition of P, Sn, or Sb are controlled to optimize Si content, P, Sn, and Sb content within specific ranges, along with a balanced Al content, to achieve reduced iron loss and enhanced magnetic flux density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If Si content is increased to reduce high-frequency iron loss, then specific resistance increases and eddy current loss decreases, but saturation magnetization decreases due to Si being a non-magnetic element
Solution Approach 1:
The patent applies local quality by creating a Si concentration gradient where the surface layer has higher Si content (5-8 mass%) than the mid-thickness part (3.4 mass% or more). This gradient structure allows the surface to have high specific resistance for reducing eddy current loss while the inner core maintains lower Si content for preserving saturation magnetization, thereby resolving the contradiction between reducing iron loss and maintaining magnetic flux density.
2Loss of energy
If high-Si steel is developed to increase specific resistance, then eddy current loss is reduced, but magnetic flux density decreases
Solution Approach 1:
The patent applies segmentation by dividing the steel sheet into distinct regions: a surface layer with high Si content (5-8 mass%) for reducing eddy current loss, and a mid-thickness part with lower Si content (3.4 mass% or more) for maintaining magnetic flux density. This segmented structure with controlled Si distribution resolves the contradiction between reducing eddy current loss and preserving magnetic flux density.
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 effectively reduces high-frequency iron loss while maintaining high magnetic flux density, as demonstrated by the specified chemical compositions and manufacturing processes, which are detailed in the patent description.
Implementation Method 1
a multilayer electrical steel sheet having both low high-frequency iron loss and high magnetic flux density
Implementation Method 2
To reduce the high-frequency iron loss, it is effective to increase specific resistance. Therefore, high-Si steel having increased specific resistance through the increase in the Si content has been developed.
Implementation Method 3
as means for achieving both high-frequency iron loss reduction and high magnetic flux density, gradient Si magnetic materials having controlled Si concentration gradient in a thickness direction of electrical steel sheets have been developed
Data Source
AI summary
Provided is a multilayer electrical steel sheet having both low high-frequency iron loss and high magnetic flux density. The multilayer electrical steel sheet has an inner layer and surface layers provided on both sides of the inner layer, in which the surface layers and the inner layer have a predetermined chemical composition, the multilayer electrical steel sheet having: ΔSi of 0.5 mass % to 4.0 mass %; ΔAl of 0.05 mass % or less; a ratio of t1 to t represented by t1/t of from 0.10 to 0.70; a magnetic flux density B10 of 1.3 T or more; and a ratio of B1 to B10 represented by B1/B10 of 0.45 or more; and an iron loss W10/1k in W/kg and the sheet thickness t in mm satisfy the following formula (1):W10/1k≤15+140×t (1).