Stator Wave-Winding Coil Configuration for Noise Reduction
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Solution Overview
Problem
The existing rotary electrical machines with concentric coils connected in parallel face challenges in reducing noise and vibration caused by circulating current, while also increasing the stator's length in the central axis or radial direction due to the need for connecting portions to avoid coil end portions.
Innovation Solution
The stator employs a wave-winding configuration with conductive wires, where each coil portion extends over multiple slots, reducing the number of times the conductive wire needs to pass over other coils, thus minimizing the stator's length and maintaining balance with respect to the magnetic pole center, thereby reducing circulating current, noise, and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If concentric coils are connected in parallel to reduce circulating current, then noise and vibration are reduced, but the stator length in central axis or radial direction increases
Solution Approach 1:
Instead of connecting coil ends on the upper side (axially outer side) as in conventional designs, this patent connects the first and second coil portions on the lower side (axially inner side) near the stator core. This inverted connection approach eliminates the need for long connecting portions extending axially, thereby reducing stator length while maintaining parallel connection benefits for reducing circulating current.
Solution Approach 2:
The patent transitions from axial connection (conventional upper-side connection) to radial/planar connection (lower-side connection near the stator core). By changing the connection dimension from axial extension to radial proximity, the stator length in the central axis direction is reduced while still achieving effective parallel connection for current distribution.
2Ease of operation
If connecting portions pass over coil end portions to connect coils, then coil connectivity is achieved, but the radial direction size of the stator increases
Solution Approach 1:
The patent extracts the connection function from the axial extension region and relocates it to the radial region near the stator core. By taking out the connecting portions from the axial path and positioning them radially near the core, the radial size increase is minimized while connectivity is maintained.
Solution Approach 2:
The connecting portions are nested within the radial space near the stator core rather than extending axially outward. This nesting approach allows the connecting portions to be accommodated within the existing radial envelope, avoiding significant increase in radial direction size.
3Ease of manufacture
If coils are positioned asymmetrically with respect to magnetic pole center, then manufacturing is simplified, but circulating current increases causing noise and vibration
Solution Approach 1:
The patent deliberately introduces asymmetry in the connection configuration: the first coil portion connects to the third coil portion on one side of the magnetic pole center, while the second coil portion connects to the fourth coil portion on the other side. This controlled asymmetry in connection positioning maintains manufacturing simplicity while ensuring balanced current distribution to prevent circulating current.
Data Source
AI summary
In this stator, a first coil portion, a second coil portion, a third coil portion, and a fourth coil portion each include a one-side coil part that is disposed so as to extend over a first slot and a third slot, and an other-side coil part that is disposed so as to extend over a second slot and a fourth slot.