Segmented Rotor Sleeve Cavities for Centrifugal Load Management
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Solution Overview
Problem
Conventional internal permanent magnet machines face reduced power density and efficiency due to increased mechanical stresses and magnet flux leakage from thicker rotor components at higher speeds, limiting the centrifugal load capacity and overall performance.
Innovation Solution
A rotor assembly with a sleeve component featuring cavities to house permanent magnets, allowing for thinner land portions and disc portions that absorb centrifugal loads, optimizing magnetic reluctance and reducing weight while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of bridges and center posts is increased for enhanced structural strength at higher speeds, then the rotor structural strength is improved, but magnet flux leakage increases significantly, reducing machine power density and efficiency
Solution Approach 1:
The rotor is divided into multiple laminations with magnets embedded in alternating poles, creating a segmented structure that reduces flux leakage paths while maintaining structural integrity at high speeds
Solution Approach 2:
The rotor uses composite construction combining multiple lamination layers with embedded permanent magnets, creating a structure that optimizes both mechanical strength and magnetic flux distribution for high-speed operation
2Strength
If the thickness of the sleeve component is increased to support higher centrifugal loads, then the centrifugal load capacity is improved, but the overall weight of the rotor increases, reducing power density
Solution Approach 1:
The sleeve thickness is optimized to minimum required values based on calculated centrifugal loads at specific speeds, using material property parameters to achieve the lightest possible structure that still meets strength requirements
Solution Approach 2:
The sleeve component has varying thickness distribution optimized for local stress conditions, with thicker sections only where centrifugal loads are highest and thinner sections where loads are lower, minimizing overall weight while maintaining structural integrity
3Power
If multiple permanent magnets are embedded in multiple laminations to increase power output, then the machine power density is improved, but the mechanical stresses in bridges and center posts are concentrated, requiring thicker structural components
Solution Approach 1:
The rotor is segmented into multiple laminations with magnets in alternating poles, distributing mechanical stresses across multiple discrete structural elements rather than concentrating them in single bridges or center posts
Solution Approach 2:
The design transitions from a single-plane magnet arrangement to a multi-lamination three-dimensional structure, distributing magnetic and mechanical loads across multiple axial layers to reduce stress concentration in any single location
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 enhances centrifugal load capacity, enabling higher speeds and increased power density with improved electrical performance, reducing the overall weight and cost of the machine.
Implementation Method 1
at least one rotor module configured to generate a magnetic field, whose magnetic field interacts with a stator magnetic field to produce a torque
Implementation Method 2
The speed at which the rotor can turn safely is limited by centrifugal loading on the permanent magnets and the overall weight, including that of the sleeve component
Data Source
AI summary
A permanent magnet machine and a rotor assembly for the permanent magnet machine. The permanent magnet machine includes a stator assembly including a stator core configured to generate a magnetic field and extending along a longitudinal axis with an inner surface defining a cavity and a rotor assembly including a rotor core and a rotor shaft. The rotor core is disposed inside the stator cavity and configured to rotate about the longitudinal axis. The rotor assembly further including a plurality of permanent magnets for generating a magnetic field which interacts with the stator magnetic field to produce torque. The permanent magnets are disposed within one or more cavities formed in a sleeve component. The sleeve component configured to include a plurality of cavities or voids therein and thus provide minimal weight to the permanent magnet machine. The permanent magnet machine providing increased centrifugal load capacity, increased power density and improved electrical performance.