Continuous Stator Winding for Closed Slots
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Solution Overview
Problem
The existing process for making stator windings in electric machines using hairpin-shaped copper bands is complex, leading to increased current resistance, numerous welding spots, complex quality controls, limitations in slot filling due to closed slots, and restricted active length, resulting in inefficiencies and higher costs.
Innovation Solution
A continuous winding process that involves bending a single strip into straps with alternating sectors to fill closed slots efficiently, reducing the need for twisting and welding, and using a two-part stator design for better slot filling and resin insulation, minimizing welding and resin usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hairpin-shaped copper bands are used with multiple welding spots, then the winding can be assembled in slots, but the current resistance increases and quality control becomes complex
Solution Approach 1:
The patent removes the twisting operation entirely from the winding process. Instead of twisting strap ends to prevent them from falling out, the continuous strap is directly inserted into the slot and fixed at the base, eliminating the harmful twisting step that creates additional welding spots and quality control issues.
Solution Approach 2:
The patent uses a continuous copper strap without joints or welding spots along its length. The strap is formed in a hairpin shape but remains a continuous piece of metal from one end to the other, eliminating the resistance and quality control problems associated with multiple welding spots.
2Ease of manufacture
If multiple welding spots are present in the winding, then the straps can be connected, but the current resistance increases
Solution Approach 1:
The patent employs a continuous copper strap that runs the entire length of the winding without any welding spots or joints. This continuous metallic path minimizes electrical resistance and energy losses compared to assembled hairpins with multiple welding connections.
3Stability of the object's composition
If twisting process is used to prevent strap ends from going out, then the straps are secured, but the process complexity increases
Solution Approach 1:
The patent completely removes the twisting operation from the manufacturing process. The continuous strap is simply inserted into the slot and fixed at the base, eliminating the complex twisting step while still preventing the strap from coming loose.
Solution Approach 2:
The continuous strap design allows for a simpler insertion and fixation process compared to assembling and twisting multiple hairpin segments. The strap maintains its position through direct fixation at the slot base without requiring twisting operations.
4Strength
If closed slots are used in the stator, then the structural integrity is improved, but the slot filling becomes difficult
Solution Approach 1:
The patent divides the continuous strap into functional segments: an external U-shaped portion for winding and connection, and an internal active portion for insertion into the closed slot. This segmentation allows the strap to be inserted from the external side while maintaining the closed slot structure.
Solution Approach 2:
Instead of inserting the winding from the traditional side, the patent inserts the continuous strap into the closed slot from the external side of the stator. This inverted insertion approach makes it possible to fill closed slots effectively while maintaining their structural advantages.
5Reliability
If resin insulation is applied extensively, then the welding areas are protected, but the production costs increase
Solution Approach 1:
The patent removes the need for extensive resin insulation by eliminating welding spots from the winding structure. Since the continuous strap has no joints requiring insulation, resin is only applied minimally at the base fixation area and for terminal connections, significantly reducing resin consumption.
6Productivity
If the active length of the winding is increased, then the machine efficiency improves, but the insertion difficulty increases
Solution Approach 1:
The continuous strap is designed with distinct segments: a long internal active portion for high efficiency, a U-shaped external portion for winding, and a base fixation portion for secure insertion. This segmentation enables long active lengths to be inserted into closed slots from the external side without compromising manufacturability.
Solution Approach 2:
The inversion of the insertion approach allows long continuous straps with greater active lengths to be inserted into closed slots from the external side, making it easier to manufacture high-efficiency windings with longer active portions compared to traditional methods.
Data Source
AI summary
A process is described, for making a continuous winding for a stator of an electric machine comprising the following steps: bending on a plane of a strip to make a strap in a single piece, which comprises first sectors to be inserted inside closed slots of a stator and connected by second bending sectors which remain outside the slots; providing a first, internal stator part comprising a plurality of longitudinal teeth, spaced by a space which makes the lower part of the slots; making the winding on the first stator part, by placing the first sectors of strap in the spaces included between the teeth; and connecting the two free ends of every strap; a continuous winding made with such process is further described.