Rotor with Push-on Windings for Synchronous Machines
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Solution Overview
Problem
Current rotors in salient pole design for current-excited synchronous machines face challenges in thermal behavior and coil winding methods, which are costly and inefficient.
Innovation Solution
A rotor design with radially extending winding grooves allows windings to be wound externally and inserted into the rotor core, using sealing strips to secure them, and employing non-round cross-section winding wires for improved copper fill factor and thermal performance, along with multiple pairs of winding grooves for better load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If windings are wound on the legs of the rotor during assembly, then the rotor can be assembled, but the manufacturing cost increases significantly and the process becomes much more complex
Solution Approach 1:
The rotor is divided into distinct components: a rotor body with pre-formed winding grooves and separate winding elements. The winding grooves are created as integral parts of the rotor body structure, allowing windings to be inserted as separate components rather than being wound in place during assembly. This segmentation enables independent manufacturing of the rotor body and windings, reducing overall manufacturing complexity and cost.
Solution Approach 2:
The winding grooves are pre-formed in the rotor body before the windings are installed. This preliminary action of creating the grooves as part of the rotor body manufacturing process eliminates the need for complex on-site winding operations during rotor assembly, significantly reducing manufacturing cost and process complexity while maintaining proper winding placement.
2Temperature
If traditional salient pole rotor design is used, then the rotor structure is simple, but the thermal behavior is poor and copper fill factor is low
Solution Approach 1:
The rotor body is designed with specific local features: winding grooves with particular geometries and orientations, and sealing strips positioned at specific locations. These local structural modifications improve heat dissipation pathways and increase copper fill factor in critical areas without requiring a complete redesign of the entire rotor structure, thus improving thermal behavior while maintaining overall structural simplicity.
Solution Approach 2:
The winding grooves extend radially through the rotor body in a direction perpendicular to the traditional winding plane, creating a three-dimensional winding arrangement. This dimensional change allows for better heat distribution and dissipation throughout the rotor volume while increasing the effective copper fill factor, improving thermal behavior without significantly complicating the rotor structure.
3Reliability
If sealing strips are added to close the winding grooves, then the windings are securely held, but the device complexity increases
Solution Approach 1:
The sealing strips are integrated with the rotor body structure, forming a unified component assembly. The sealing strips are positioned within the winding grooves and work together with the groove geometry to secure the windings, creating a combined structural system that provides reliable winding retention without requiring separate complex retention mechanisms, thus improving reliability while minimizing additional complexity.
Data Source
AI summary
A rotor for an electrical machine has a rotor core with a center line, which forms an axis of rotation. The rotor core can be subdivided by a plurality of imaginary radial planes, which extend radially from the axis of rotation at regular angular intervals. For each radial plane, at least one pair of winding grooves is formed, which extend through the rotor core to either side of the radial plane with the radial plane serving as the plane of symmetry. A winding is arranged in each pair of winding grooves, in winding receiving areas of the winding grooves, which winding extends through the two winding grooves of the pair. Each winding groove is bounded in its winding receiving area on its side facing the assigned radial plane by a side face, which continues in a manner free from projections, in the sense of projections in a direction away from the radial plane, from the winding receiving area to the radially outer end of the winding groove.