Stator with Closure Element for Rotary Electric Machine
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Solution Overview
Problem
Existing rotating electrical machine stators with serrated yokes and distributed windings face issues with electromagnetic disturbances and increased magnetic losses due to sudden permeance variations, leading to pulsating torques and reduced performance.
Innovation Solution
A stator design featuring a serrated crown with tangentially connected teeth and notches that allow for distributed winding placement, where windings pass through non-adjacent slots, and a yoke attached to the crown, facilitating easier access and improved filling rates, reducing electromagnetic disturbances and enhancing torque and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the notches are completely open or semi-open towards the air gap to allow easy winding insertion, then the ease of manufacture is improved, but electromagnetic disturbances and magnetic losses increase due to flux fringes and sudden permeance variations
Solution Approach 1:
A closure element is introduced as an intermediary component between the notch and the air gap. This closure element partially closes the notch opening, reducing flux fringes and electromagnetic disturbances while still allowing the notch to serve its function of housing the winding. The closure element acts as a mediator that reconciles the conflicting requirements of easy winding insertion and reduced electromagnetic interference.
Solution Approach 2:
The closure element is positioned specifically at the opening of the notch towards the air gap, providing localized magnetic shielding where it is most needed. This local modification allows the rest of the notch structure to remain open for winding insertion, while the closure element locally reduces flux fringes and permeance variations. The solution applies local quality by modifying only the critical region rather than the entire notch structure.
2Ease of operation
If the notches are open towards the air gap to facilitate winding access, then the ease of operation is improved, but the filling rate and electromagnetic performance deteriorate
Solution Approach 1:
The closure element serves as a mediator that enables both easy winding access and improved filling rate. During the winding insertion process, the closure element can be temporarily moved or opened to allow access, then positioned to close the notch for optimal electromagnetic performance. This intermediary component facilitates the transition between the operational state (open for insertion) and the performance state (closed for optimal magnetic properties).
3Device complexity
If traditional open notches are used, then the device complexity is reduced, but the volume torque and machine performance decrease due to electromagnetic disturbances
Solution Approach 1:
The closure element is a relatively simple component that can be added to existing notch structures without fundamentally redesigning the entire stator. It serves as a minimal-complexity intermediary that delivers significant performance improvements in volume torque and electromagnetic characteristics. The closure element's simple geometry and straightforward integration make it an efficient solution that minimizes added complexity while maximizing performance gains.
4Power
If more magnetic laminations are used to improve electromagnetic performance, then the power and efficiency increase, but the manufacturing cost and weight increase
Solution Approach 1:
The closure element extracts and addresses the root cause of electromagnetic disturbances (flux fringes at open notch surfaces) without requiring additional magnetic lamination material. By closing the notch openings, the solution eliminates the source of magnetic losses and permeance variations, thereby improving electromagnetic performance without adding weight or requiring more magnetic laminations. This extraction approach solves the problem at its source rather than compensating with additional materials.
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 minimizes harmonics, increases torque, reduces magnetic noise, and lowers manufacturing costs by optimizing conductor placement and reducing the necessary magnetic material, while allowing operation at high speeds and large sizes with improved induction levels.
Implementation Method 1
an increase in the 'magnetic' air gap due to the flux fringes
Implementation Method 2
windings arranged in a distributed manner in the notches, having electrical conductors arranged in a row in the notches
Data Source
Figure 1~1a
Figure 2a~2c
Figure 3~6
AI summary
The present invention relates to a stator (2) for a rotary electric machine (10), comprising: a toothed ring (25) comprising teeth (23) defining notches (21) therebetween, said notches being open radially toward the outside, windings (22), which are arranged in a distributed manner in the notches (21), electrical conductors being arranged in an aligned manner in the notches (21), and a yoke (29) mounted onto the toothed ring.