Electric Machine Bushing Cooling Circuit Design
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Solution Overview
Problem
Existing cooling systems for rotating electric machines, particularly those using tubular elements to connect bushings, suffer from inefficient cooling due to water temperature optimization issues and mechanical stress transmission, leading to unreliable connections and potential leakages.
Innovation Solution
An optimized cooling system where tubular elements connect bushings with a U-shaped zone between each couple to limit stress transmission and enhance heat exchange, utilizing an external cooling circuit with optimized water temperature, and deformable conductive connections to improve reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If water cooling circuit is used to cool the stator and bushings, then cooling efficiency is improved, but the water temperature becomes suboptimal when reaching tubular elements
Solution Approach 1:
The cooling system is segmented into two independent circuits: a first cooling circuit for the stator and a second cooling circuit for the tubular elements. This segmentation allows each circuit to operate with independently optimized water temperatures, ensuring that the tubular elements receive cooling water at the optimal temperature rather than receiving already-warmed water from the stator cooling circuit.
2Reliability
If tubular elements are used to connect bushings, then electrical connection is achieved, but mechanical stress transmission causes deformations
Solution Approach 1:
A deformable connection element is introduced as an intermediary between the bushings and the tubular elements. This deformable connection element absorbs mechanical stresses and thermal expansions, preventing stress transmission to the tubular elements while maintaining reliable electrical and fluid connections. The deformable nature of this intermediary component allows it to accommodate dimensional changes without compromising connection integrity.
3Strength
If deformable conductive connection with multiple small pipes is used between bushings and tubular elements, then stress transmission is reduced, but connection reliability decreases due to potential leakages
Solution Approach 1:
Multiple separate small pipes for water passage and electrical conductors for power transmission are merged into a single integrated tubular element. This consolidation eliminates the multiple connection points that could potentially leak, while the deformable connection element maintains flexibility and stress absorption capabilities. The unified tubular structure provides both electrical conductivity and fluid passage without the reliability issues of multiple separate connections.
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 solution provides a more reliable and efficient cooling system for rotating electric machines, reducing mechanical stress and leakages while maintaining efficient cooling, allowing for easier maintenance with minimal downtime.
Implementation Method 1
an electric conductive, deformable connection between the bushings and the tubular elements must be provided... because the tubular elements deform according to the temperature
Implementation Method 2
the water moving out from the stator passes through the bushings to cool them
Implementation Method 3
an optimized cooling system where tubular elements connect bushings with a U-shaped zone between each couple to limit stress transmission and enhance heat exchange
Data Source
Figure 1~2
AI summary
The electric machine (1) comprises a casing (2) housing a stator (3) with stator windings (3a), a rotor (4), bushings (6, 7) penetrating the casing (2) and having a first portion (9) inside of the casing (2) and a second portion (10) outside of the casing (2). The stator windings (3a) are connected to the first portion (9) of the bushings (6, 7). Some of the bushings (7) have the second portions (10) connected together by an element (12). The element (12) is connected to a water cooling circuit (13). The water cooling circuit (13) is external to the casing (2).