Stator core
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Solution Overview
Problem
Brushless permanent magnet motors face challenges in size, weight, power density, manufacturing cost, efficiency, reliability, and noise, particularly in the design of stator cores which affect flux linkage and winding fill factor.
Innovation Solution
A stator core design with angled arms creating a trapezoidal winding channel, asymmetric pole faces, and overmoulded bobbins to enhance winding fill factor, reduce height, and minimize flux leakage, while allowing for efficient manufacturing and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the first and second portions of the arms are both orthogonal to the back with the same overall length, then the structure is simple and easy to manufacture, but the height of the wound stator core is increased and the winding fill factor is reduced
Solution Approach 1:
The patent applies asymmetry by making the second portions of the first and second arms obliquely angled relative to the first portions, rather than both being orthogonal. This asymmetric configuration allows the arms to converge toward one another, defining a trapezoidal winding channel that reduces the overall height of the wound stator core while accommodating windings effectively.
2Power
If the second portions of the first and second arms are angled toward one another, then the height of the stator core is reduced and power density is increased, but the complexity of the design increases
Solution Approach 1:
The patent applies parameter changes by specifying that the second portions of the arms are angled at around 20 to 40 degrees (for example, around 26-30 degrees) relative to the respective first portions. This quantitative parameter optimization provides a good compromise between reducing the height of the stator core and maximizing the cross-sectional area of the winding channel, thereby increasing power density while maintaining manufacturability.
3Power
If the pole faces extend to either side of the respective second portions of the first and second arms, then flux linkage to the rotor assembly is increased and torque density is improved, but the risk of flux leakage to adjacent stator cores increases
Solution Approach 1:
The patent applies dimensionality change by angling the second portions of the arms toward one another, which increases the distance between adjacent stator cores in the radial dimension. This spatial separation in another dimension effectively reduces flux leakage between adjacent stator cores while still allowing the pole faces to extend to either side of the second portions for increased flux linkage and torque density.
4Power
If the winding channel has a generally trapezoidal cross-sectional shape, then the fill factor is increased and power density is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing each arm into two distinct portions: a first portion extending substantially orthogonally relative to the back, and a second portion obliquely angled relative to the first portion. This segmentation allows the trapezoidal winding channel to be formed through the geometric arrangement of discrete structural elements, making the complex geometry achievable through standard manufacturing processes while maintaining high fill factor and power density.
Data Source
AI summary
A stator core for a brushless permanent magnet motor has a back, and first and second arms extending from the back. Each of the first and second arms has a first portion extending substantially orthogonally relative to the back, and a second portion obliquely angled relative to the first portion.