Cage Rotor Support Ring Structure for High-Speed Operation
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Solution Overview
Problem
Cage rotors in asynchronous machines are limited by the mechanical strength of materials used in short-circuit rings, restricting rotational speeds to around 5000 rpm due to centrifugal forces, and the dimensions of retaining rings are restricted by installation considerations.
Innovation Solution
A cage rotor design incorporating a magnetically conductive body with axially running slots and short-circuit rings, featuring a high-strength supporting element connected to the short-circuit rings via material-fit connections, primarily to absorb centrifugal forces without guiding current, allowing for rotational speeds up to 8000 rpm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If short-circuit rings are made from materials with high electrical conductivity (aluminum, copper, copper alloys), then electrical conductivity is improved, but mechanical strength deteriorates, limiting rotational speeds to approx. 5000 rpm
Solution Approach 1:
The invention uses a composite structure consisting of an inner supporting element made of high-strength material (steel or copper alloy) and an outer short-circuit ring made of highly conductive material (aluminum or copper). The supporting element absorbs centrifugal forces while the outer ring guides current, allowing rotational speeds above 8000 rpm while maintaining both mechanical strength and electrical conductivity.
2Strength
If retaining rings are provided on the outer diameter of short-circuit rings to reinforce them, then mechanical strength is improved, but the dimensions are restricted by installation considerations in the air gap
Solution Approach 1:
Instead of placing the reinforcing element on the outer diameter of the short-circuit ring, the invention inverts the approach by placing the high-strength supporting element on the inner side of the short-circuit ring. This allows the supporting element to absorb centrifugal forces without protruding into the air gap, avoiding installation space constraints while still providing mechanical reinforcement.
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 design enables higher rotational speeds and increased motor or generator output while maintaining mechanical stability and efficiency, with low electrical losses and improved cooling through radial extensions and airflow.
Implementation Method 1
the supporting element being connected to the short-circuit ring, at least at predefined sections on the inner side of the short-circuit ring, with a material fit to the short-circuit ring. The supporting element is made of mechanically high-strength material, which due to its comparatively poor electrical conductivity is not used and suitable to guide a current, but instead is primarily provided for absorbing the centrifugal forces of the short-circuit ring during operation of the asynchronous machine.
Implementation Method 2
In this context, 'material-fit connection' is understood to mean welding, such as electron beam welding or hot isostatic pressing (HIP) or soldering, for example.
Implementation Method 3
In this context, 'material-fit connection' is understood to mean welding, such as electron beam welding or hot isostatic pressing (HIP) or soldering, for example.
Data Source
AI summary
A cage rotor of an asynchronous machine includes a magnetically conductive body having substantially axially running slots with conductors connected to end faces of the magnetically conductive body in an electrically conductive manner by short circuit rings. The short circuit rings have an outer side, an inner side, a front side, and a rear side. A supporting element made of a high-strength material is located at least radially within the short circuit rings, i.e. on the inner face, with the supporting element being connected to the short-circuit ring, at least in one section, with a material fit.