Segmented Stator Coating for Rotating Electrical Machine Stability
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Solution Overview
Problem
Conventional rotating electrical machines face destabilizing effects due to small air gaps between the stator and rotor, especially when operating in high-density, corrosive fluids, leading to sub-synchronous frequencies and reduced stability.
Innovation Solution
The stator is equipped with a protective coating that has recessed parts facing the rotor, allowing for improved fluid circulation and reducing gas-related stiffness and damping effects by increasing the volume around the rotor, thus preventing the formation of a rotating gas film and enhancing thermal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a regular cylindrical protective coating is applied to the stator, then the stator is protected against the aggressive environment, but the air gap between the coating and rotor becomes small (0.5-10 mm), causing gas sealing effects that destabilize the suspension
Solution Approach 1:
The protective coating is segmented axially into multiple sections with varying lengths, creating discrete zones rather than a continuous cylinder. This segmentation allows gas to circulate through the gaps between sections, preventing the gas sealing effect while maintaining protective coverage over the windings and pole pieces.
Solution Approach 2:
The solution transitions from a two-dimensional continuous cylindrical surface to a three-dimensional structured arrangement of discrete axial sections with interstitial spaces. This dimensional change introduces new pathways for gas flow through the coating structure, eliminating the gas sealing effect that occurs with continuous coatings.
2Volume of stationary object
If the air gap between the protective coating and rotor is reduced to minimize the volume of aggressive gas, then the machine size is reduced, but gas-related direct and crossed stiffness and damping effects increase, detrimental to suspension stability
Solution Approach 1:
The protective coating is divided into multiple axial sections of different lengths, creating a segmented structure that occupies less overall volume than a continuous coating while providing equivalent protection. The segmentation allows gas circulation pathways that reduce destabilizing gas effects.
Solution Approach 2:
The protective coating uses thin-walled cylindrical sections that provide adequate protection against the aggressive environment while minimizing the volume occupied by the coating itself. The thin-walled design allows gas to pass through the interstitial spaces between sections, reducing gas sealing effects.
3Object-affected harmful factors
If a long cylindrical protective coating is used to ensure complete protection of the windings, then the protection coverage is improved, but the length of the coating increases the gas sealing effect and destabilizing mass effects
Solution Approach 1:
The protective coating is divided into multiple axial sections of different lengths arranged in a segmented pattern. This segmentation provides complete protective coverage over the windings and pole pieces while creating gaps between sections that allow gas circulation, thereby reducing the destabilizing effects associated with long continuous coatings.
Solution Approach 2:
Different axial sections of the protective coating have different lengths, creating local variations in the coating structure. This local quality variation allows the coating to provide complete protection where needed while maintaining open pathways for gas flow, reducing the overall destabilizing gas effects without compromising protection coverage.
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 significantly reduces the destabilizing effects of high-density gases, improves thermal conditions, and maintains stability by facilitating gas movement and reducing sub-synchronous excitation phenomena, even at high rotor speeds.
Implementation Method 1
improve the circulation of the cooling fluid (the high density gas) in the air gap
Implementation Method 2
the destabilizing effects of the gas are all the more important when the gas is dense (at high pressure), when the air gap is small and when the length is important
Data Source
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AI summary
The invention relates to a rotating electrical machine including at least one piece of electrical equipment formed by a canned or overmoulded electric motor or a canned or overmoulded magnetic suspension system. The aforementioned piece of electrical equipment comprises a rotor (102) and a stator (150) including pole pieces (154) and windings (152). The surface of the stator (150) facing the rotor (102) is provided with at least one sleeve (101) or a coating (190) that provides protection against corrosive conditions. The sleeve (101) or the protective coating (190) on the surface of the stator (150) facing the rotor (102) is provided with parts (111) which are recessed in relation to the main surfaces (155) defining the air gap (e), said recessed parts (111) being distributed along the edge of the stator, thereby stimulating the movement of the fluid flowing in the air gap around the rotor (102).