Stator Core Geometry for Rotating Machine Resonance Noise Reduction
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Solution Overview
Problem
Rotating electrical machines experience noise due to vibrations caused by resonance, which occurs when the natural frequency aligns with the operating frequency, particularly when the ratio of yoke thickness to tooth length is within a specific range, and concentrated winding enhances vibrational excitation forces.
Innovation Solution
The design satisfies the equation La/2−Lb/2=Lc+Ld, with 0.15≤Lb/La≤0.35 and Lc/Ld≥0.35, to optimize the length and thickness of the yoke and teeth, reducing noise by increasing the natural frequency beyond the operating range and minimizing tooth vibrations through concentrated winding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the shaft member length is shortened to suppress rotor loss in high-speed rotation, then rotor loss is reduced, but the gap length between shaft member and tooth end surface must be shortened, which limits the available space for coils and constrains the yoke-tooth length ratio
Solution Approach 1:
The patent changes the geometric parameters of the stator core, specifically setting the yoke thickness to be 0.05 to 0.20 times the tooth length (Lc/Ld = 0.05 to 0.20). This parameter optimization allows the design to accommodate shortened shaft members while maintaining appropriate gaps and coil spaces, thus resolving the contradiction between reducing rotor loss and maintaining structural flexibility.
2Ease of manufacture
If concentrated winding is used to simplify coil structure, then manufacturing is simplified, but the electromagnetic force is not distributed to each tooth, resulting in larger vibrational excitation forces and increased noise
Solution Approach 1:
The patent applies local quality by optimizing the specific geometric dimensions of the stator core components. By setting the yoke thickness to 0.05 to 0.20 times the tooth length, the structure locally enhances vibration resistance at critical positions (yoke-tooth junction) while maintaining concentrated winding throughout the machine, thus reducing noise without sacrificing manufacturing simplicity.
3Device complexity
If the yoke thickness decreases as tooth length increases to maintain the ratio, then the natural frequency may fall within the operating frequency range, causing resonance and vibration-induced noise
Solution Approach 1:
The patent optimizes the yoke thickness parameter to be 0.05 to 0.20 times the tooth length, which maintains structural proportion balance while ensuring the natural frequency remains outside the operating frequency range. This parameter optimization prevents resonance and vibration-induced noise while preserving the balanced structural design.
4Object-generated harmful factors
If distributed winding is used to distribute electromagnetic force to each tooth, then vibrational excitation force is reduced, but the coil structure and manufacturing process become more complex
Solution Approach 1:
The patent uses concentrated winding with optimized local geometric parameters (yoke thickness = 0.05 to 0.20 times tooth length) to achieve vibration reduction without the complexity of distributed winding. The local structural optimization compensates for the lack of force distribution, maintaining manufacturing simplicity while reducing vibrational excitation.
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 configuration effectively reduces noise generated by vibrations by ensuring the natural frequency exceeds the operating range, thereby suppressing resonance and minimizing tooth vibrations, even in machines with high-speed shafts.
Implementation Method 1
the coils 62 are each wound around a corresponding one of the teeth 72 by concentrated winding... an electromagnetic force that causes a vibrational excitation force applied to the teeth
Implementation Method 2
a bearing 14 that rotatably supports the shaft members 40
Implementation Method 3
a rotor 19 that includes shaft members 40 and a magnetic body 30... a stator 60 that includes a stator core 61 and coils 62
Data Source
AI summary
A rotating electrical machine includes a rotor including a magnetic body and a shaft member, a stator including a stator core and coils, and a bearing rotatably supporting the shaft member. the stator core includes a yoke and teeth. The following equation is satisfied: La/2−Lb/2=Lc+Ld, wherein a point at a center of the yoke is defined as a center point, La/2 represents a length from the center point to an intersection point, Lb/2 represents a length from the center point to an intersection point, Lc represents a thickness of the yoke, and Ld represents a length of each of the teeth and wherein conditions of 0.15≤Lb/La≤0.35 and Lc/Ld≥0.35 are satisfied.