AFPM Stator Structure for Direct Oil Cooling and Higher Space Factor
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Solution Overview
Problem
Axial flux permanent magnet (AFPM) motors face challenges with temperature management, space factor optimization, and cooling efficiency due to complex force transmission paths and reduced space between coils, which affects performance and cooling efficiency.
Innovation Solution
The design incorporates a tapered stator core with divided bobbins and housings made of engineering plastic, allowing for direct oil cooling and reduced coil resistance through a simplified structure with a hollow space between coils, supported by an inner and outer housing configuration using plastic fusion methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If T-shaped supports are inserted between stacked stator cores, then the stator structure is supported, but the area of coils is reduced and space factor is reduced
Solution Approach 1:
The stator structure is segmented into modular components: stacked stator cores, separate bobbins, and T-shaped supports. This segmentation allows each component to be optimized independently - the bobbins provide coil support without occupying coil space, while T-shaped supports provide structural stability between cores.
Solution Approach 2:
T-shaped supports act as intermediary elements between the stacked stator cores and the bobbins. They provide mechanical support and force transmission without directly interfering with the coil winding area, as the bobbins are positioned on the outer circumferential surface where the T-shaped supports engage.
2Reliability
If T-shaped supports are pressed in via press-fitting, then the support is secured, but manufacturing precision is reduced due to small press-fitting amount from tolerance
Solution Approach 1:
The design incorporates tolerance compensation mechanisms in the press-fitting interface of T-shaped supports. The support structure includes features that accommodate manufacturing variations, ensuring reliable securing even when press-fitting precision is reduced by tolerance accumulation.
Solution Approach 2:
The press-fitting parameters (force, depth, tolerance ranges) are optimized to balance between securing reliability and manufacturing feasibility. The T-shaped support geometry is designed to distribute contact forces, reducing the sensitivity to press-fitting precision variations.
3Force
If T-shaped supports are used, then force transmission is provided, but multiple force transmission paths are created and robustness is degraded
Solution Approach 1:
The force transmission function is extracted and concentrated into dedicated T-shaped support components rather than being distributed through multiple complex paths. Each T-shaped support provides a direct, simplified force transmission path from the stator core stack to the housing, reducing the number of transmission paths while maintaining robustness.
4Area of stationary object
If coils are wound tightly, then space factor is improved, but oil flow path is blocked and cooling efficiency is reduced
Solution Approach 1:
The coil assembly incorporates localized oil flow channels and cooling passages within the bobbin structure and stator core gaps. These local cooling features allow oil to flow through specific regions without disrupting the overall tight winding configuration, maintaining both high space factor and effective cooling.
Solution Approach 2:
The bobbin material or coil insulation may incorporate porous structures that allow oil penetration and cooling while maintaining the tight winding configuration. This enables thermal management without compromising the space factor.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the space factor, improves cooling efficiency by enabling direct oil cooling, and reduces coil resistance, thereby enhancing the performance of AFPM motors.
Implementation Method 1
The plurality of bobbins is coupled to the inner housing and the outer housing by a plastic fusion method. The plastic fusion method may include any one of laser fusion, bonding, ultrasonic fusion, or the like.
Data Source
AI summary
An AFPM motor stator includes a plurality of stator cores in a circular arrangement. Each of the plurality of stator cores is shaped in a tapered shape. The stator also includes a plurality of bobbins each divided to be coupled to an outer side of each of the plurality of stator cores and a plurality of coils each wound along an outer circumferential surface of each of the plurality of bobbins. The stator also includes an inner housing provided in a shape of a hollow cylinder and supporting radially-inner portions of the plurality of bobbins each wound by a coil of the plurality of coils and includes an outer housing surrounding and supporting radially-outer portions of the plurality of bobbins each wound by the coil.