Bent Conductor Cross-Section Coil for Lower AC Loss
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Solution Overview
Problem
Existing coils with electric wires wound once or helically suffer from significant losses due to uneven current distribution and backflow currents, particularly when alternating current is applied.
Innovation Solution
The coil design features an electric wire with a conductor having an elongated cross-sectional shape that is bent such that its ends are away from the central axis, suppressing backflow currents and uneven current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an electric wire with a circular cross-sectional shape is used in a coil, then the coil structure is simple and easy to manufacture, but loss increases due to uneven current distribution and backflow currents
Solution Approach 1:
The patent applies asymmetry by changing the conductor cross-section from a symmetric circular shape to an asymmetric shape where the centroid is shifted away from the geometric center. This asymmetric configuration prevents backflow currents and promotes uniform current distribution, thereby reducing energy loss while maintaining manufacturing feasibility through standard wire drawing processes.
Solution Approach 2:
The patent implements local quality by creating non-uniform current distribution characteristics through the asymmetric cross-sectional shape. The shifted centroid creates regions of different current density that collectively eliminate backflow effects, optimizing local current flow patterns to reduce overall energy loss in the coil.
2Loss of energy
If an electric wire with a non-circular cross-sectional shape is used to reduce loss, then energy transmission efficiency improves, but the coil structure becomes more complex
Solution Approach 1:
The patent uses asymmetry to achieve the dual benefit of reduced energy loss and controlled structural complexity. The asymmetric cross-section with shifted centroid is designed to be manufacturable using conventional processes, avoiding excessive complexity while effectively eliminating backflow currents and improving energy transmission efficiency.
3Loss of energy
If an electric wire with a bent elongated cross-sectional shape with ends away from the central axis is used, then backflow current and uneven current distribution are suppressed, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality by creating specific regional characteristics in the conductor cross-section. The bent elongated shape with ends positioned away from the central axis creates localized current flow patterns that suppress backflow effects. This geometric configuration can be achieved through controlled rolling or drawing processes with standardized tolerances, balancing manufacturing precision requirements with energy loss reduction.
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
This design effectively reduces losses in coils with electric wires wound once or helically, improving efficiency in electric power transmission.
Implementation Method 1
Such a coil, however, has been known to suffer from uneven distribution of a flow of a current due to a skin effect and a proximity effect of the electric wire
Implementation Method 2
Such a coil, however, has been known to suffer from uneven distribution of a flow of a current due to a skin effect and a proximity effect of the electric wire
Data Source
Figure 1~2
Figure 3~4
Figure 5(a)~6(b)
AI summary
A coil (100A) includes an electric wire (1) wound around a central axis (2) once or helically a plurality of times. The electric wire (1) includes a conductor (10) having an elongated cross-sectional shape (11) in a plane including the central axis (2). The cross-sectional shape (11) is bent such that a first end (12) and a second end (13) in a longitudinal direction are away from the central axis (2). Loss in the coil including the electric wire wound once or helically a plurality of times is thus reduced.