Figure 8 Linked Coils for Fractional Slot Motor Winding
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Solution Overview
Problem
Fractional slot type motors with complicated winding layouts face challenges in automation due to a large number of coils and crossover lines, leading to increased production steps and manufacturing failures.
Innovation Solution
A three-phase alternating current motor with figure 8-shaped linked coils and a method for manufacturing using an inserter type automatic winding machine, where coils are produced with reduced crossover lines and inserted into the stator with a simplified winding layout, reducing production steps and facilitating automation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If distributed winding is used in fractional slot type motor with 6N>3P, then cogging torque and torque ripple are reduced, but the number of coils increases and winding layout becomes complicated
Solution Approach 1:
The patent divides the complex distributed winding into modular units by linking coils in figure 8-shape configurations. This segmentation groups multiple coils into standardized units that can be systematically arranged, reducing the overall complexity of the winding layout while maintaining the distributed winding structure needed for low torque ripple.
Solution Approach 2:
The patent employs nested arrangement where figure 8-shaped linked coils are positioned within slot structures in a hierarchical manner. The linked coils are nested within the stator slots following specific patterns that optimize space utilization and simplify the winding process, allowing complex windings to be built from simpler nested components.
2Extent of automation
If a large number of coils are produced by automatic winding machine, then winding automation is achieved, but the number of production steps increases and manufacturing complexity increases
Solution Approach 1:
The patent merges multiple individual coil windings into figure 8-shaped linked coil units that are wound and inserted as integrated structures. This combining approach reduces the total number of separate insertion operations required, thereby decreasing production steps while maintaining automation compatibility.
Solution Approach 2:
The patent performs preliminary linking of coils into figure 8-shape configurations during the winding process itself, rather than assembling them separately afterward. This preliminary action of creating linked units during winding reduces subsequent assembly steps and streamlines the manufacturing process.
3Reliability
If the number of slots 6N is more than 3 times the number of pole pairs P, then cogging torque and torque ripple become smaller, but the coil pitch becomes larger than 1 slot requiring distributed winding
Solution Approach 1:
The patent addresses the increased coil pitch requirement by transitioning from simple planar coil arrangements to three-dimensional figure 8-shaped linked coil structures. This dimensional change allows the coils to span multiple slots (pitch greater than 1) while maintaining manufacturability through the standardized linked configuration that simplifies the distributed winding process.
Data Source
AI summary
In a motor, the number of slots 6N divided by the number of pole pairs P (2N>P) of a rotor is an irreducible fraction, when a quotient obtained by dividing 6N by 2P is denoted by X, 2N coils per phase are arranged in the slots of the stator, one and another one of the coils connected in series thereto are arranged overlapping in one center slot while sharing one side with aligned current directions, opposite sides of the two coils not sharing the slot are each arranged in other ones of the slots at a distance by X from the center slot, so that the two coils are arranged while being linked in a figure 8-shape straddling over the three slots, and N sets per phase of the linked coils are arranged at not completely overlapping positions in the slots and are connected in series.