Shunt Resistor Skin Effect Control via Local Quality
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Solution Overview
Problem
Conventional shunt resistors face challenges in accurately detecting high-frequency currents due to the skin effect, which causes current to concentrate at the edges, leading to increased resistance values and reduced detection accuracy.
Innovation Solution
A rod-shaped shunt resistor with a through hole or high resistance part along its axis, where the resistance body is made of resistance alloy material, and main electrodes are bonded to the end faces, reducing the fluctuation band of the current pathway and minimizing resistance value changes caused by high-frequency currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a plate-shaped resistance body is used, then the resistance value is low and current detection accuracy is good, but skin effect causes current to concentrate at corners, increasing resistance value at high frequencies
Solution Approach 1:
The resistance body is designed with non-uniform cross-sectional area along its length, creating different local properties. The central portion has a smaller cross-sectional area than the end portions, which concentrates current flow in specific regions and reduces skin effect influence at high frequencies while maintaining low overall resistance.
2Reliability
If the cross-section of resistance body is made circular, then resistance value change by skin effect is reduced, but current still concentrates at outer part, and resistance value fluctuation remains
Solution Approach 1:
The resistance body features a circular cross-section with varying radial distribution of electrical resistance. The central axis region has higher resistance while the outer region has lower resistance, creating a specific current distribution pattern that reduces skin effect impact and maintains stable resistance values across frequency ranges.
3Reliability
If a through hole or high resistance part is added to the resistance body, then current pathway fluctuation is reduced and skin effect is controlled, but device complexity increases
Solution Approach 1:
The resistance body's cross-sectional area is continuously varied along its length, creating a tapered or stepped structure where the central portion has smaller area and end portions have larger area. This geometric parameter change achieves the desired current distribution and skin effect control without requiring additional components like through holes or separate high resistance parts.
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 design effectively controls the skin effect, allowing for accurate current detection up to higher frequencies by concentrating the current pathway at the low resistance part, thereby reducing resistance value fluctuations and enabling reliable high-frequency current detection.
Implementation Method 1
as shown in left figure of FIG. 1, high frequency current C flows by skin effect at part in corner of resistance body 11 shown by hatching, and the current becomes difficult to flow at central portion of the resistance body. Accordingly, resistance value rises since effective area of high frequency current flowing decreases.
Data Source
AI summary
Provided is a shunt resistor, which controls an influence of skin effect by high frequency current. The shunt resistor has a rod-shaped resistance body (11), and a pair of main electrode (12), of another material from the resistance body, wherein end faces of the resistance body and the main electrode are bonded. The resistance body (11) has a hole (11a) going through in direction where main electrodes are disposed, or a high resistance part (11b) going through at its axis portion that is highly resistive than outer part, and low resistance part (11c) that is formed in outer of the high resistance part. It is preferable that outer circumference of the resistance body is circle-shaped. Since, current doesn't flow fundamentally in the through hole or the high resistance part, fluctuation band in the current pathway can be reduced. Therefore, change of resistance value by skin effect by high-frequency current can be reduced.