Rotor Pole Shoe Plate Design for Vibration Reduction
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Solution Overview
Problem
Large synchronous salient-pole machines face vibration issues due to electromagnetically induced thermal deformation of pole shoes during asynchronous start-up, leading to imbalance and vibration problems caused by temperature differences between the pole shoes and shafts.
Innovation Solution
A rotor design with a pole shoe plate attached to the radially outer surface of the pole shoe body, featuring flexible connections and profiling such as bulges, grooves, and slots, which allows for elastic deformation and reduced eddy current propagation, maintaining mechanical and electrical conductivity while minimizing temperature equalization between the plate and body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pole shoe is made as a solid integral structure, then the mechanical strength is improved, but the thermal deformation during asynchronous start-up causes vibration and imbalance
Solution Approach 1:
The pole shoe is divided into two separate parts: a pole shoe body and a pole shoe plate. The pole shoe plate is attached to the radially outer surface of the pole shoe body at multiple connection points. This segmentation allows the plate to deform independently due to eddy currents while the body maintains structural integrity, resolving the contradiction between mechanical strength and thermal deformation resistance.
Solution Approach 2:
The pole shoe plate is made flexible between connection points by incorporating bulges and/or grooves, creating local flexibility only where needed. This allows the plate to accommodate thermal deformation from eddy currents during asynchronous start-up while maintaining overall structural strength through the rigid connection points and body.
2Object-affected harmful factors
If the pole shoe plate is made flexible to accommodate thermal deformation, then the vibration behavior is improved, but the mechanical connection stability may be compromised
Solution Approach 1:
The pole shoe plate is segmented into multiple zones by connection points, with flexible regions between them. This segmentation allows localized deformation in non-critical areas while maintaining stability at the connection points where the plate attaches to the pole shoe body.
Solution Approach 2:
Flexibility is introduced locally between connection points through bulges and/or grooves, while the connection points themselves maintain rigid mechanical and electrical contact. This creates a structure with spatially varying properties: flexible where needed for vibration reduction, stable where needed for structural integrity.
3Strength
If multiple connection points are used to attach the pole shoe plate, then the mechanical strength is improved, but the thermal conduction between plate and body increases
Solution Approach 1:
The connection points are segmented and distributed at specific locations on the pole shoe body, avoiding continuous thermal conduction paths. This segmentation of the connection structure allows mechanical strength through multiple attachment points while limiting thermal conduction by creating discrete, isolated connection zones.
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 improves the vibration behavior of the rotor by allowing the pole shoe plate to deform independently of the pole shoe body, reducing thermal deformation and maintaining efficient operation and conductivity, thus enhancing the rotor's balance and performance.
Implementation Method 1
the pole shoe plate being flexible between the connection points at least in the axial direction by means of bulges and/or grooves
Implementation Method 2
temperatures of several hundred degrees Celsius can occur on the surfaces of the pole shoes... large shearing forces can occur at a parting line between the pole shoe and the pole shaft
Implementation Method 3
During the asynchronous start-up of a synchronous salient-pole machine, eddy currents are induced in the pole shoes placed thereon, with the surface of the pole shoes in particular being strongly heated by alternating magnetic fields, in particular by eddy currents
Implementation Method 4
the pole shoe plate being connected to the pole shoe body at a plurality of connection points
Data Source
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AI summary
The invention relates to a rotor (3) for an electric rotating machine (1), in particular a synchronous machine (1a), comprising a shaft (5) that can rotate about an axis of rotation (4) and at least one pole shoe (7). According to the invention, in order to improve the vibration properties, the pole shoe (7) comprises a pole shoe body (8) and a pole shoe sheet metal (9), the pole shoe sheet metal (9) resting on a radially outer surface (8a) of the pole shoe body (8).