Axial-Gap Stator Core Structure for Flux Passage and Low Cogging
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Solution Overview
Problem
Existing axial-gap rotary electric machines face challenges in achieving high torque and manufacturability due to issues with magnetic flux passage and cogging torque, particularly in the assembly and design of cores with flange portions.
Innovation Solution
A core design featuring an annular yoke and columnar teeth with frame-shaped flange portions, where the yoke and teeth are composed of a single powder compact, and the flange portions have through-holes with a high exposed area ratio, allowing for efficient magnetic flux passage and preventing coil displacement, while minimizing cogging torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the yoke and teeth are composed of a single powder compact with flange portions, then the manufacturability and assembly are improved, but the magnetic flux passage and cogging torque characteristics deteriorate
Solution Approach 1:
The core is divided into modular components: a body portion containing the yoke and teeth formed as a single powder compact, and separate flange portions that are fixed to the end portions of the teeth. This segmentation allows the body to be optimized for magnetic flux passage while flange portions provide manufacturing and assembly benefits, resolving the contradiction between ease of manufacture and magnetic flux passage reliability.
Solution Approach 2:
Different regions of the core are given different properties: the body portion (yoke and teeth) is formed as a single powder compact with optimized magnetic properties for flux passage, while the flange portions are separate components with optimized geometric properties (through-hole design, exposed area ratio of 7.5% or more) that facilitate manufacturing and assembly without compromising the magnetic circuit integrity.
2Ease of operation
If the flange portions are designed with through-holes and high exposed area ratio, then the coil displacement prevention and assembly are improved, but the device complexity increases
Solution Approach 1:
The flange portions integrate multiple functions into a single component structure: they provide mechanical support for coil placement, prevent coil displacement through the through-hole design, and facilitate assembly by being fixed to the tooth end portions. The through-hole design allows the end portion of each tooth to be inserted and exposed at a ratio of 7.5% or more, combining structural support with assembly simplicity, thereby reducing overall device complexity despite the detailed geometric design.
3Reliability
If the end surface area of teeth is increased to 7.5% or more of flange portion area, then the magnetic flux passage is improved, but the cogging torque increases
Solution Approach 1:
The design optimizes the exposed area ratio parameter to be 7.5% or more of the flange portion area, which ensures adequate magnetic flux passage through the teeth. This parameter is carefully selected to balance two competing requirements: sufficient exposed area for magnetic flux passage while limiting the area to prevent excessive cogging torque. The through-hole design and specific exposed area ratio represent a precise parameter optimization that resolves the contradiction between magnetic flux passage reliability and cogging torque reduction.
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
The design enables the construction of rotary electric machines with high torque and excellent manufacturability by ensuring effective magnetic flux passage and reducing cogging torque, thereby enhancing the assembly and performance of axial-gap rotary electric machines.
Implementation Method 1
The yoke and the teeth are composed of a single powder compact
Data Source
AI summary
A core that is used in an axial-gap rotary electric machine and that includes a body, and frame-shaped flange portions. The body includes an annular yoke and columnar teeth that are arranged in a circumferential direction of the yoke. The flange portions are fixed to end portions of the respective teeth. The yoke and the teeth are composed of a single powder compact. Each of the flange portions is composed of a powder compact that has a through-hole. The end portion of each of the teeth is inserted in the through-hole, and an end surface of each of the teeth is exposed from the through-hole. A ratio of an area of the end surface of each of the teeth to an area within an outer circumferential edge of each of the flange portions is 7.5% or more in a plan view in an axial direction of the yoke.