Arcuate Grain Orientation in Electric Machine Cores
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Solution Overview
Problem
Rotary electric machines with cylindrical cores constructed from non-oriented ferrous materials do not fully leverage the magnetic performance benefits of grain-oriented ferrous materials, such as higher permeability and lower losses, due to the linear grain alignment along the rolling direction, which limits their efficiency in applications like motors and generators.
Innovation Solution
The use of grain-oriented ferrous materials, such as 3% silicon steel, is extended to cylindrical stator and rotor cores in rotary electric machines, with a circular or radial grain orientation, enabling the construction of efficient cylindrical cores through a spiral winding process, and the integration of radially-projecting teeth with linear grain orientation to enhance magnetic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear grain-oriented ferrous materials are used in cylindrical cores, then manufacturing is simplified with standard rolling processes, but magnetic performance is limited due to misalignment with the circular flux path
Solution Approach 1:
The patent applies curvature by transitioning from linear grain orientation to circular/arcuate grain orientation in the ferrous material. The grain flow is shaped to follow the circular flux path around the cylindrical core, creating a curved grain structure that aligns with the magnetic flux trajectory, thereby reducing magnetic losses while maintaining manufacturing feasibility through modified rolling processes
2Loss of energy
If circular grain orientation is achieved through spiral winding, then magnetic performance improves with higher permeability and lower losses, but manufacturing complexity increases
Solution Approach 1:
The patent changes the grain orientation parameter from linear to circular/arcuate through modified rolling processes. By adjusting the rolling direction and applying cross-rolling techniques, the grain structure is reoriented to follow circular paths, achieving superior magnetic performance while controlling manufacturing complexity through process optimization rather than complex assembly
3Use of energy by moving object
If grain-oriented ferrous materials are used, then magnetic permeability increases by at least 30 percent, but the linear grain alignment limits efficiency in rotary applications
Solution Approach 1:
The patent adapts grain-oriented ferrous materials to cylindrical geometry by creating circular or arcuate grain patterns that follow the curved flux path. This curved grain orientation enables the material to maintain its high permeability and low loss properties while being fully adapted to rotary electric machine applications, resolving the adaptability limitation of linear grain structures
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 approach results in rotary electric machines with improved magnetic performance, higher permeability, and lower losses, enabling more efficient power transmission and generation, suitable for various motor and generator applications, including cycloidal and switched reluctance machines.
Implementation Method 1
Magnetic wall domains of the resulting material are aligned such that the ferrous material has high permeability along the direction of grain orientation
Implementation Method 2
This accounts for the material's anisotropic material properties
Implementation Method 3
winding the strip into one or more circular turns, each having a circular or arcuate grain orientation when the circular turn(s) is/are viewed along a center axis of the cylindrical core
Data Source
AI summary
A rotary electric machine, e.g., a cycloidal reluctance motor, includes a stator having stator teeth connected to a cylindrical stator core, and a rotor having a cylindrical rotor core. The stator core and/or rotor core are constructed of grain-oriented, spirally-wound ferrous material having a circular or annular grain orientation. The stator teeth may be constructed of grain-oriented steel having a linear grain orientation. Notches may be spaced around an inner circumferential surface of the stator core, with each stator tooth engaged with a respective notch. The rotor may be eccentrically positioned radially within the stator. The rotor core may define notches spaced around its outer circumferential surface, with salient rotor projections engaged with a respective rotor notch. The machine in such an embodiment may be a switched reluctance rotor. An electrical system using the machine and a method of manufacturing the machine are also disclosed.