Stator Tooth Notching for AC Traction Motor Noise Reduction
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Solution Overview
Problem
AC traction motors produce significant electromagnetic noise due to radial electromagnetic forces, which current noise reduction methods have not adequately addressed, limiting their application in certain fields.
Innovation Solution
An optimization design method that involves determining the main factors of noise generation, modifying the motor's magnetic circuit to increase magnetic reluctance by opening square notches at symmetrical positions on the stator teeth, and using finite element analysis to fit functional equations for optimal notch and slotting position sizes across various power grades to reduce electromagnetic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise reduction methods (changing slot combination, skewed rotor design, changing air-gap length) are used, then some noise reduction is achieved, but the noise reduction effect is insufficient to meet practical requirements
Solution Approach 1:
The patent changes the geometric parameters of the stator teeth by opening square notches at specific positions, which modifies the magnetic circuit characteristics and reduces the radial electromagnetic force harmonics. This parameter change approach directly addresses the insufficient noise reduction of conventional methods by introducing a new structural parameter (notch size and position) that can be optimized for better performance.
Solution Approach 2:
The patent applies local quality modification by opening notches only at specific symmetrical positions on the stator teeth rather than uniformly modifying the entire structure. This localized modification targets the specific regions where magnetic flux concentration occurs, thereby reducing electromagnetic noise more effectively while minimizing structural changes.
2Object-affected harmful factors
If the stator tooth structure is modified to open square notches, then electromagnetic noise is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent segments the stator tooth structure by opening discrete square notches at specific positions rather than modifying the entire tooth structure. This segmentation approach simplifies the manufacturing process compared to complete structural redesign, as only specific locations require modification while the overall stator tooth geometry remains intact.
3Object-affected harmful factors
If the magnetic circuit is modified to increase magnetic reluctance, then the radial electromagnetic force is reduced, but the motor's magnetic performance may be affected
Solution Approach 1:
The patent carefully controls the parameters of the notches (size, position, depth) to achieve the desired increase in magnetic reluctance without excessively impacting the overall magnetic performance. By optimizing these parameters, the radial electromagnetic force is reduced while maintaining acceptable magnetic performance for motor 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
Effectively reduces electromagnetic noise by 21.95% to 22.54% without affecting other performance indicators, achieving a better noise reduction effect through the optimal design of stator teeth slotting.
Implementation Method 1
increase the magnetic reluctance of the motor stator core
Implementation Method 2
reduce the air-gap magnetic flux density
Implementation Method 3
radial electromagnetic force in air-gap field on the inner wall of the stator
Implementation Method 4
vibrations of stator core and casing under the action of radial electromagnetic force
Data Source
AI summary
To solve the problem of large electromagnetic noise in AC traction motor, embodiments have open square notches at symmetrical positions on both sides of stator teeth of AC traction motor to effectively reduce electromagnetic noise without affecting other performance indicators of motor. In addition, embodiments fit the functional relationship between the optimal notch size or optimal slotting position size of motors and their power by determining the optimal notch size or optimal slotting position size of motors with different power grades, so as to achieve the noise reduction effect.