Grain-Oriented Electrical Steel for Lower Transformer Inrush Current
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Solution Overview
Problem
Existing methods to control excitation inrush current in transformers, such as controlling voltage phase angle, require complex control and ancillary equipment, leading to increased costs and equipment size.
Innovation Solution
A grain-oriented electrical steel sheet with controlled residual magnetic flux density, produced through magnetic domain refining using a high-energy beam with an orifice to focus and eliminate the beam periphery, reducing cutoff residual magnetic flux density to 1.00 T or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If voltage phase angle control is used to decrease excitation inrush current, then excitation inrush current is reduced, but device complexity and cost increase
Solution Approach 1:
The patent extracts and addresses the root cause of excitation inrush current by focusing on residual magnetic flux in the iron core. Instead of controlling voltage phase angle through complex external systems, the invention modifies the magnetic properties of the steel sheet itself through magnetic domain refining treatment, thereby eliminating the need for complex control equipment.
Solution Approach 2:
The patent replaces the electrical control system (voltage phase angle control) with a material property modification approach. By using high-energy beam irradiation to refine magnetic domains in the grain-oriented electrical steel sheet, the invention substitutes complex electrical control mechanisms with a one-time material treatment process that inherently reduces residual magnetic flux.
2Object-generated harmful factors
If voltage phase angle control equipment is installed to decrease excitation inrush current, then excitation inrush current is reduced, but equipment size and cost increase
Solution Approach 1:
The patent removes the need for ancillary control equipment by directly addressing the source of excitation inrush current through magnetic domain refining treatment of the steel sheet. This eliminates heavy control devices and ancillary equipment from the transformer system.
3Object-generated harmful factors
If residual magnetic flux is reduced through material modification, then excitation inrush current decreases, but manufacturing complexity increases
Solution Approach 1:
The patent changes the magnetic domain structure parameters of the grain-oriented electrical steel sheet through high-energy beam irradiation. By controlling parameters such as beam energy, irradiation pattern, and treatment conditions, the invention achieves reduced residual magnetic flux while maintaining a relatively simple manufacturing process that integrates well with existing steel sheet production.
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 suppresses excitation inrush current without increasing equipment complexity or costs, maintaining low iron loss properties.
Implementation Method 1
when a surface of the steel sheet that has undergone final annealing is irradiated with a high-energy beam to undergo magnetic domain refining treatment
Implementation Method 2
magnetic domain refining by strain introduced from at least one surface of the steel sheet to the interior of the steel sheet
Data Source
AI summary
Provided is a grain-oriented electrical steel sheet capable of effectively suppressing the generation of excitation inrush current when used as transformer iron core material. In a grain-oriented electrical steel sheet subjected to magnetic domain refining, when magnetization varying with a sine wave at 50 Hz is generated in the rolling direction of the grain-oriented electrical steel sheet and power supply is cut off when the magnetization reaches 1.50 T, then cutoff residual magnetic flux density Br, which is the magnetic flux density 0.1 s after the cut off, is 1.00 T or less.