End Plate Radial Adjustment for Electric Machine Rotor Alignment
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Solution Overview
Problem
Unbalanced magnetic pull (UPM) causes undesirable vibrations in electric machines due to rotor misalignment with the stator, leading to interference forces and suboptimal rotation, particularly in high-frequency motors with small air gaps.
Innovation Solution
An end plate with radially adjustable support elements, or shimming pads, is designed to align the rotor concentrically with the stator, allowing for precise adjustment of the magnetic bearing's center to coincide with the stator's geometrical and magnetic axes, reducing periodic force excitations and vibrations through adjustable protrusions and shim configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotor is mounted using a magnetic bearing in the end plate, then the rotor can be rotatably supported, but the rotor may become misaligned with the stator due to manufacturing tolerances, causing unbalanced magnetic pull and vibrations
Solution Approach 1:
The support elements are made radially adjustable, allowing the end plate to be dynamically repositioned relative to the stator housing. This enables compensation for manufacturing tolerances and achieves precise concentricity between the rotor and stator, eliminating unbalanced magnetic pull while maintaining reliable rotor support.
Solution Approach 2:
The radial position of the support elements is changed as a parameter to adjust the end plate's position. By varying the protruding amount of the support elements, the system achieves optimal alignment between rotor and stator, resolving the alignment precision issue while preserving support stability.
2Device complexity
If fixed support elements are used in the end plate, then the structure is simple, but the rotor cannot be precisely aligned with the stator to avoid vibrations
Solution Approach 1:
The support elements transition from a fixed structure to a dynamically adjustable one. This allows the end plate to be precisely positioned relative to the stator housing, achieving the required rotor concentricity while adding only minimal complexity through the adjustment mechanism.
3Manufacturing precision
If the support elements are made radially adjustable, then the rotor can be precisely aligned to reduce vibrations, but the device complexity increases
Solution Approach 1:
The radial position of support elements is adjusted as a controllable parameter to achieve precise alignment. This parameter-based approach allows systematic control of rotor-stator concentricity, achieving high manufacturing precision while managing device complexity through structured adjustment mechanisms.
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 effectively reduces undesirable vibrations and eccentricities of the rotor, optimizing its alignment and operational stability by allowing for fine adjustments based on vibration behavior and assembly tolerances, thereby improving the rotor's concentricity and reducing UPM-related issues.
Implementation Method 1
a magnetic bearing equipped for rotatably mounting a rotor of the electric machine
Implementation Method 2
an active magnetic bearing with associated catch bearing, wherein the catch bearing comprises an inner ring which encloses the rotor shaft and which has an inner diameter that is greater by a predetermined dimension than an outer diameter of the rotor shaft, so that in the case of an energized magnetic bearing an annular gap between rotor shaft and inner ring is formed
Data Source
AI summary
An end plate for an electric machine includes: a bearing receptacle in which a magnetic bearing which is configured for rotatably mounting a rotor of the electric machine can be accommodated; and a radially outwardly pointing circumferential contour on which a number of at least three supporting elements are provided, which supporting elements each protrude radially beyond the circumferential contour by a determined protruding amount, with the result that the supporting elements define a discontinuous external circumferential contour of the end plate. The respective protruding amounts of the support elements are dimensioned such that the end plate can be fitted in by making a center of the magnetic bearing correspond to at least one of a geometric longitudinal axis of the electric machine and a magnetic longitudinal axis of the electric machine.