Segment Conductor Stator Bends for Lower Loss and Crack Resistance
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Solution Overview
Problem
In existing segment conductor type stators, the twisted apex portions of the spanning portions lead to increased conductor length, resulting in higher conduction losses and potential insulation deterioration due to crack propagation in the electrical insulation film.
Innovation Solution
The stator design incorporates a stator core with tubular slots and conductor segments featuring a linear electrical conductor, an insulation film, hollow capsules dispersed within the insulation, and a bent-back shape at the axial end. The capsules at the bend's periphery are ellipsoid in shape, which helps in limiting crack propagation and reducing the radius of curvature of the bend.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the apex portions of the spanning portions are twisted to form a crossed state, then interference between coil segments is avoided and the height of the spanning portions is limited, but the length of electrical conductors is increased resulting in increased conduction loss
Solution Approach 1:
Instead of twisting the apex portions outward to achieve compact height, the invention inverts the approach by forming bends that extend toward the radially inner side of the stator core. This reverse configuration maintains the height limitation while reducing conductor length by directing the bends inward rather than outward, thereby resolving the contradiction between compact shape and energy loss.
2Shape
If the apex portions are twisted and bulged toward the radially outer side, then the coil segments can be arranged with limited height, but the electrical insulation film is stretched and cracked leading to insulation deterioration
Solution Approach 1:
The invention inverts the conventional approach of bulging apex portions outward by forming bends toward the radially inner side. This reversal prevents the stretching and cracking of the electrical insulation film that occurs with outward bulging, while still achieving the desired limitation on coil end portion height, thus maintaining both shape control and insulation reliability.
Solution Approach 2:
The invention provides beforehand cushioning by forming bends with controlled radius of curvature that prevent excessive stress concentration on the electrical insulation film. By pre-configuring the bend geometry to extend inward rather than outward, the design anticipates and prevents the cracking issue before it occurs, protecting the insulation integrity while achieving compact height.
3Loss of energy
If the radius of curvature of the bend is reduced to limit the height of the coil end portion, then the conduction loss is reduced, but the electrical insulation film is more likely to crack and propagate
Solution Approach 1:
The invention applies local quality by differentiating the capsule shapes based on their location relative to the bend. Capsules at the outer periphery of the bend are formed with larger radius of curvature to prevent cracking in high-stress regions, while capsules at the inner periphery have smaller radius of curvature. This localized differentiation allows the overall bend radius to be reduced for lower conduction loss while maintaining insulation stability through strategic capsule placement and sizing.
Data Source
AI summary
A stator includes: a stator core that is shaped in a tubular form and has a plurality of slots; and a plurality of conductor segments that are inserted into the slots and are electrically connected with each other to form a stator coil. Each conductor segment has: an electrical conductor that is shaped in a linear form; an electrical insulation film that covers a periphery of the electrical conductor; a plurality of capsules that are hollow and are dispersed inside the electrical insulation film; and a bend that forms a bent-back shape on the conductor segment at an end portion of the stator core which faces in an axial direction. Among the plurality of capsules, capsules located at an outer periphery of the bend and capsules located at an inner periphery of the bend are respectively shaped in an ellipsoid form at each of the plurality of conductor segments.