Stator Busbar Downsizing via Phase Winding Inversion

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Solution Overview

Problem

Existing stator designs for electric rotating machines face challenges in downsizing the busbar unit, which affects the mass, cost, and vibration durability due to the uneven spacing of power and neutral points.

Innovation Solution

The stator design incorporates a cylindrical stator core with segment conductors wound in specific patterns for the U-phase, V-phase, and W-phase coils, where the neutral point of the third phase winding is positioned between the power points of the first and second phase windings, and the power point of the third phase winding is between the neutral points of the first and second phase windings, allowing for closer proximity of these points and enabling a more compact busbar unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional stator designs with segment coils are used, then the stator can be manufactured with standard winding patterns, but the busbar unit becomes large in size and mass due to uneven spacing of power and neutral points

Engineering Contradiction:

Improvestandard winding patternVSAvoidbusbar unit mass

Core Design Contradiction:

Ease of manufactureVSWeight of stationary object

Solution Approach 1:

The patent applies inversion by reversing the conventional winding direction for the third phase winding. While first and second phase windings progress in one circumferential direction, the third phase winding progresses in the opposite direction. This inversion causes the power point and neutral point of the third phase to swap positions relative to conventional designs, enabling the neutral point to be disposed between the power points of first and second phase windings, and the power point to be disposed between the neutral points, thereby achieving compact busbar unit arrangement

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent introduces asymmetry in the winding configuration by having the third phase winding progress in the opposite circumferential direction compared to the first and second phase windings. This asymmetric approach creates non-uniform spacing patterns that allow power and neutral points to be positioned closer together, reducing the overall busbar unit size while maintaining electrical performance

Inventive Principle:

Principle #4Asymmetry

2Ease of manufacture

If conventional stator designs are used, then manufacturing processes are simple, but the busbar unit has low natural frequency and poor vibration durability

Engineering Contradiction:

Improvewinding process simplicityVSAvoidvibration durability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

By inverting the winding direction of the third phase, the patent achieves a compact busbar unit configuration that increases the natural frequency of the busbar assembly. The swapped positioning of power and neutral points creates a more rigid structural arrangement, improving vibration durability and reliability without complicating the manufacturing process

Inventive Principle:

Principle #13The other way round (Inversion)

3Stability of the object's composition

If power and neutral points are evenly spaced in conventional designs, then electrical balance is maintained, but the busbar unit size increases and cost increases

Engineering Contradiction:

Improveelectrical balanceVSAvoidbusbar unit volume

Core Design Contradiction:

Stability of the object's compositionVSVolume of stationary object

Solution Approach 1:

The inversion of the third phase winding direction strategically repositions power and neutral points to achieve closer spacing. This maintains electrical balance through the symmetric arrangement of the three phases while significantly reducing the busbar unit volume and associated manufacturing costs

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11496009B2Stator, electric rotating machine, and electric-powered vehicle

Publication Date: 2022.11.08 SUBARU CORP

AI summary

A stator includes a stator core, first to third phase windings, and a busbar unit. Each of the first to third phase windings includes segment conductors inserted into slots of the stator core, and has a power point and a neutral point each protruding from an end face of the stator core. The busbar unit includes first to third power busbars coupled respectively to the power points of the first to third phase windings, and a neutral busbar coupled to the neutral points of the first to third phase windings. In circumferential directions of the stator core, the neutral point of the third phase winding is disposed between the power points of the first and second phase windings, and the power point of the third phase winding is disposed between the neutral points of the first and second phase windings.