Electric Machine Stator Support Neck Asymmetry
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Solution Overview
Problem
Medium to large-sized electric machines experience significant 2F vibration excitations due to stator deformation, which are transmitted to the frame and cause noise, with existing solutions either being costly or reducing electrical performance, and there is a need to prevent these excitations from reaching the frame end shields.
Innovation Solution
The support arrangement between the stator and the frame is modified by spatially shifting the side support necks to be out-of-phase, effectively canceling the excitation of symmetric vibration modes, thereby reducing the transmission of 2F excitations to the frame end shields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the thickness of the stator yoke is increased or additional cylindrical stiffeners are added to reduce excitation forces, then the vibration transmission is reduced, but the manufacturing cost increases and/or the electrical performance decreases
Solution Approach 1:
The patent applies asymmetry by positioning the support necks at non-symmetric locations around the stator circumference. Specifically, the necks are arranged at angular positions that break the rotational symmetry, creating an asymmetric support pattern that prevents resonant vibration transmission while maintaining electrical performance and avoiding additional stiffening structures.
2Object-affected harmful factors
If passive dampers are added to increase damping of bearing shield vibration modes, then the vibration amplitudes are reduced, but additional components are introduced into the electric machine
Solution Approach 1:
The patent extracts the vibration control function from separate damping components and integrates it into the stator support structure itself. By designing the support necks with specific geometric parameters and positioning them at optimized locations, the stator structure provides inherent vibration isolation without requiring additional passive dampers or damping components.
3Productivity
If the electric machine operates at rotational speeds corresponding to resonance speeds, then the electrical performance is maintained, but the vibration amplitudes become very high due to low damping of shield vibration modes
Solution Approach 1:
The patent applies preliminary action by pre-configuring the stator support necks with optimized geometric parameters and angular positions before operation. This pre-design ensures that the support structure inherently provides vibration isolation across the operational speed range, preventing resonance amplification without requiring active control or speed limitations during operation.
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 arrangement reduces the amplitude of axial vibrations by 85% without adverse effects on the electric machine's performance, making it suitable for medium to large-sized machines with a pole number greater than two, especially effective in four-pole machines.
Implementation Method 1
The stator deformation may be transmitted to the frame via the support arrangement between the stator and the frame. The stator deformations, i.e. excitations, may occur in the radial direction, but the vibrations are transmitted all over the frame and the surroundings as noise.
Implementation Method 2
The support arrangement between the stator and the frame is modified by spatially shifting the side support necks to be out-of-phase, effectively canceling the excitation of symmetric vibration modes, thereby reducing the transmission of 2F excitations to the frame end shields.
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The electric machine comprises a stator and a frame. The stator is supported with support necks (P1, P2, P3, P4) on the frame in at least two axially (Z1-Z1) spaced support locations. The support locations comprise a first group of support necks (P1, P2) and a second group of support necks (P3, P4). The support necks in the first group are positioned in connection with a vertical centre plane (Y1-Y1). The second group comprises two side support necks positioned opposite to each other at an angular distance above or below a horizontal centre plane (X1-X1). The angular distance is defined by a first angle (α1) which is determined in degrees by the formula α1 = (90/P) ± (1/5)*(90/P), where P is the number of poles of the electric machine and P > 2.