10-Pole 9-Slot Synchronous Motor Tooth Tip Optimization
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Solution Overview
Problem
Conventional synchronous motors with a 2:3 ratio of magnetic poles to stator slots generate uneven rotating magnetic fields, leading to unbalanced attraction and repulsion forces between the rotor and stator, resulting in vibration and noise due to cogging torque and pulsations.
Innovation Solution
A 10-pole/9-slot synchronous motor design where the central tooth's circumferential width and radial thickness are smaller than the adjacent teeth, optimizing the magnetic field distribution and reducing the excitation force, thereby minimizing vibration and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If windings are concentratedly wound around three adjacent teeth for one phase, then the rotating magnetic field is generated unevenly, but this generates unbalanced attraction and repulsion forces causing large excitation force and vibration
Solution Approach 1:
The patent applies local quality by making the circumferential width and radial thickness of the central tooth tip portion different from those of the both-side tooth tip portions. Specifically, the central tooth has a smaller circumferential width and radial thickness at its tip portion compared to the adjacent teeth. This local modification creates a more balanced magnetic field distribution in the concentrated winding configuration, reducing unbalanced attraction and repulsion forces between the rotor and stator, thereby decreasing excitation force and resulting vibration and noise.
2Reliability
If openings are provided between adjacent teeth, then magnetic flux interlinkage is facilitated and short-circuiting is prevented, but cogging torque is generated causing vibration and noise
Solution Approach 1:
The patent maintains the opening structure between adjacent teeth for facilitating magnetic flux interlinkage and preventing short-circuiting, but applies local quality modification to the tooth tip portions. By making the central tooth's tip portion have different dimensions (smaller circumferential width and radial thickness) compared to the both-side teeth, the patent locally adjusts the magnetic field distribution near the openings. This reduces the disturbance of magnetic flux density distribution that would otherwise occur near the openings, thereby reducing cogging torque while preserving the beneficial flux interlinkage function.
3Object-generated harmful factors
If 10 poles and 9 slots are used, then pulsations occur 90 times per rotation, but the amplitude of cogging torque decreases due to distributed energy
Solution Approach 1:
The patent accepts the 10-pole/9-slot configuration which naturally distributes cogging torque energy over 90 pulsations per rotation, reducing the amplitude of cogging torque. The local quality modification to the central tooth tip portion further optimizes this configuration by creating more balanced magnetic field distribution, thereby enhancing the reduction of vibration and noise while maintaining the acceptable pulsation frequency characteristic.
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 effectively reduces vibration and noise while maintaining efficiency by balancing the magnetic field and reducing the excitation force, enhancing the motor's performance and output.
Implementation Method 1
openings are provided in order to facilitate interlinkage of the magnetic fluxes generated by the permanent magnets disposed in the rotor with the stator windings
Implementation Method 2
magnetic fluxes generated because of the electric current flowing in the stator windings
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A synchronous motor includes a stator that includes nine teeth that are divided into three phases, each of which includes three adjacent teeth, windings 2 being concentratedly wound around the teeth. The circumferential width w1 of a tip portion 30b of a central tooth 30 among three teeth forming each phase is made smaller than the circumferential widths w2 and w3 of tip portions 31b and 32b of both-side teeth 31 and 32, and the tooth thickness t1 of the tip portion 30b of the central tooth 30 is made smaller than the tooth thicknesses t2 and t3 of the tip portions 31b and 32b of the both-side teeth 31 and 32.