Slip Ring Body Layout for Lower Eddy Current Heating
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Solution Overview
Problem
In double-fed asynchronous machines, the induction of electrical eddy currents in magnetically conductive materials by conductor bars leads to significant heat losses, necessitating complex and costly cooling solutions, which are economically unattractive due to the high cost of materials like copper required to reduce eddy currents.
Innovation Solution
A slip ring body design with recesses in one slip ring allowing conductor bars from another slip ring to pass through, where the area around the recess has lower magnetic conductivity, reducing eddy current intensity, and using an air gap or a material with lower magnetic conductivity in the recess area to minimize heat losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If magnetically conductive materials (e.g., stainless steel) are used for slip rings, then electrical and magnetic conductivity is improved, but eddy current losses increase causing excessive heat generation
Solution Approach 1:
The patent applies local quality by creating a composite structure where the slip ring has different magnetic conductivity in different areas. The base material (stainless steel) provides high electrical and magnetic conductivity, while inserted elements (non-magnetic materials like copper or aluminum, or magnetic shielding materials) are placed specifically in regions where eddy currents are generated. This local modification reduces eddy current losses without compromising the overall electrical conductivity needed for power transmission.
2Loss of energy
If copper is used for slip rings, then eddy current losses are reduced due to low magnetic conductivity, but material cost increases significantly
Solution Approach 1:
The patent employs composite materials by combining stainless steel (providing high electrical conductivity and structural integrity) with non-magnetic or low-magnetic-conductivity materials (such as copper, aluminum, or non-magnetic alloys) inserted into specific regions. This composite structure achieves the eddy current reduction benefit of copper-like materials while maintaining the cost-effectiveness and mechanical properties of stainless steel, avoiding the need to use expensive copper throughout the entire slip ring.
Solution Approach 2:
The patent applies parameter changes by modifying the magnetic conductivity parameter locally within the slip ring structure. Instead of changing the base material from stainless steel to copper (which would increase cost), the invention introduces inserted elements that change the magnetic conductivity parameter in specific regions where eddy currents occur. This allows optimization of eddy current losses while maintaining cost-effectiveness by using stainless steel as the base material.
3Temperature
If complex cooling solutions are implemented, then heat dissipation is improved, but device complexity and cost increase
Solution Approach 1:
The patent converts the harmful effect of eddy current losses into a beneficial design feature by strategically placing non-magnetic or low-magnetic-conductivity materials within the slip ring structure. These inserted elements, which would normally be seen as adding complexity, actually serve to reduce eddy current losses at the source, thereby reducing heat generation in the first place. This eliminates or reduces the need for complex cooling systems, as the harmful eddy currents are prevented rather than managed.
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
Significantly reduces heat losses by minimizing eddy currents, achieving improved heat management with lower technical and financial expenditure compared to traditional cooling methods.
Implementation Method 1
The conductors carrying three-phase current induce eddy currents in adjacent magnetically conductive materials, which in turn lead to heating of the respective components due to ohmic losses
Implementation Method 2
The conductors carrying three-phase current induce eddy currents in adjacent magnetically conductive materials, which in turn lead to heating of the respective components due to ohmic losses
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a slip ring body (1) for electrically contacting an asynchronous machine, comprising at least one first slip ring (2) and a second slip ring (3), each of which is secured to at least two respective conductor bars (11a, 11b, 12a, 12b, 13a, 13b, 21a, 21b, 24a, 24b, 32a, 32b, 34a, 34b, 42). At least two slip rings (2, 3) are rigidly connected together, and at least one of the slip rings (2, 3) has at least one slip ring (14, 15, 16, 17, 18, 19) which is designed for passing through the conductor bars (11a, 11b, 12a, 12b, 13a, 13b, 21a, 21b, 24a, 24b, 32a, 32b, 34a, 34b, 42) of the at least one other slip ring (2, 3). The slip ring body (1) is characterized in that the at least one slip ring (2, 3) which has the at least one recess (14, 15, 16, 17, 18, 19, 23, 26, 27, 28, 29, 30, 37, 43, 44, 45) has a lower magnetic conductivity in a region about the recess (14, 15, 16, 17, 18, 19, 23, 26, 27, 28, 29, 30, 37, 43, 44, 45) than in a region in which the respective at least two conductor bars (11a, 11b, 12a, 12b, 13a, 13b, 21a, 21b, 24a, 24b, 32a, 32b, 34a, 34b, 42) are attached to the slip ring or the region is designed to contact an energy-transmitting brush. The two regions are not made of copper, and the region about the recess (14, 15, 16, 17, 18, 19, 23, 26, 27, 28, 29, 30, 37, 43, 44, 45) is at least partly filled with air.