Stator Slot Wedge Structure for Conductor Retention and PDIV
Solution Overview
Problem
Efficient insertion and reliable retention of conductors within the stator core of electric machines are challenging, and obtaining accurate partial discharge inception voltage (PDIV) measurements is difficult due to existing design limitations.
Innovation Solution
The design incorporates a stator core with radially inward teeth, minicaps, slots, and wedges that are friction-fit to secure conductors, along with slot liners to improve conductor positioning and retention, facilitating better PDIV measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional slot designs are used, then conductor insertion is simplified, but conductor retention is unreliable and PDIV measurements are inaccurate
Solution Approach 1:
The slot structure is segmented into multiple functional components: the base slot, slot liner, and wedge assembly. The wedge itself is segmented into legs that fit between conductors and a body that provides retention. This segmentation allows each component to perform its specific function optimally while maintaining overall reliability.
Solution Approach 2:
The slot liner acts as an intermediary component between the slot and the conductors, providing a smooth surface for conductor insertion while the wedge serves as an intermediary retention mechanism that secures conductors without direct metal-to-metal contact. These intermediary elements improve retention reliability without requiring complex direct engagement structures.
2Manufacturing precision
If tight slot openings are used, then conductor positioning is improved, but insertion difficulty increases
Solution Approach 1:
The slot liner is pre-installed in the slot before conductor insertion, creating a prepared pathway with appropriate clearance. This preliminary action allows conductors to be inserted easily while the liner ensures precise final positioning. The wedge is also pre-positioned to engage with conductors at the appropriate insertion stage.
Solution Approach 2:
The slot liner serves as a mediator between the tight slot geometry and the conductors, providing a controlled interface that guides conductors into precise positions while maintaining ease of insertion. The liner's material properties allow it to accommodate insertion forces while ensuring accurate final positioning.
3Reliability
If wedges are positioned radially inward from conductors, then retention is improved, but access for insertion becomes difficult
Solution Approach 1:
Instead of positioning the wedge entirely radially inward from the conductors, the design inverts the approach by having the wedge legs extend radially outward between the conductors and slot liner, while the wedge body remains radially inward. This inverted configuration allows the insertion tool to access the wedge from the radially outward direction through the slot opening, making insertion easy while the radially inward body provides reliable retention.
Solution Approach 2:
The wedge design utilizes multiple radial dimensions: the legs extend in one radial direction (outward) for insertion access, while the body is positioned in another radial direction (inward) for retention. This dimensional approach allows the wedge to fulfill both insertion and retention functions simultaneously without compromise.
4Reliability
If friction-fit wedges are used, then conductor security is enhanced, but manufacturing complexity increases
Solution Approach 1:
The friction-fit wedge design allows the wedge to secure itself to the conductors through friction forces generated during insertion and operation. The wedge legs are shaped to create natural friction engagement with the conductors and slot liner, eliminating the need for additional fastening mechanisms, adhesives, or complex assembly steps. The structure is self-retaining through its geometric design.
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 enhances the insertion and retention of conductors, providing improved performance and more accurate PDIV measurements by securely positioning wedges between conductors and slot liners, reducing partial discharge occurrences.
Implementation Method 1
Each wedge is friction fit in the slot with the first leg wedged on one side of said slot and the second leg wedged on an opposite side of said slot
Data Source
AI summary
A stator for an electric machine includes a stator core defining an axial direction, a first end, and a second end. The stator core includes a plurality of slots formed between a plurality of teeth, wherein each of the plurality of slots extend from the first end to the second end of the stator core and define a slot opening on a radially inward portion of the stator core. A plurality of conductors are positioned in each of the slots and are connected together to form a winding arrangement for the stator. A wedge is positioned in each slot of the stator core radially inward from the plurality of conductors positioned in said slot. The wedge includes a first leg positioned on one side of the slot, a second leg positioned on an opposite side of the slot, and a bridge spanning across the slot opening.