Embedded Rotor Magnet Disk Layout for High-Speed Power Density
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Solution Overview
Problem
Conventional electric machines face challenges in achieving high specific power and efficiency due to increased stresses and costs associated with high rotational speeds, particularly in disk architectures where thicker magnets and larger rotor disks are required to manage centrifugal forces and magnetic flux.
Innovation Solution
An electric machine design featuring a rotor disk with continuous embedded magnets of alternating polarity along the circumferential direction, which reduces the need for thick magnets and larger rotor disks, allowing for improved magnetic flux utilization and higher speed operation while minimizing weight and size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional two rotor magnet architecture is used, then magnetic flux can be maintained, but thicker magnets and larger rotor disk are required resulting in increased weight and size
Solution Approach 1:
The patent merges the functions of two separate rotor magnets and rotor back irons into a single integrated rotor magnet with embedded alternating polarity portions. This consolidation eliminates redundant components and reduces overall rotor weight while maintaining the necessary magnetic flux path through the rotor disk to both stator assemblies.
Solution Approach 2:
The integrated rotor magnet performs multiple functions simultaneously: it generates magnetic flux, provides the magnetic return path, and supports itself without requiring separate rotor back irons. The alternating polarity portions embedded within the magnet create multiple flux paths that serve both stator assemblies, making the single magnet universally functional.
2Power
If high rotational speeds are used, then power-to-weight ratio increases, but stresses on rotating components increase requiring larger and heavier retaining structures
Solution Approach 1:
By integrating the rotor magnet directly into the rotor disk structure, the design eliminates separate retaining structures that would add weight. The magnet itself becomes part of the rotating assembly, reducing overall rotor weight and improving power-to-weight ratio while the embedded alternating polarity portions provide structural reinforcement.
Solution Approach 2:
The rotor assembly uses composite construction with the integrated rotor magnet embedded in the rotor disk, creating a unified structure that optimizes both strength and weight. This composite approach allows the rotor to withstand high rotational speeds without requiring heavier retaining structures.
3Power
If conventional disk architecture with two rotor magnets is used, then magnetic flux can be returned to stator assemblies, but additional rotor back irons are required resulting in increased costs, size, and weight
Solution Approach 1:
The patent combines the rotor magnet and rotor back iron functions into a single integrated component. The alternating polarity portions embedded within the rotor magnet create the necessary magnetic flux return paths to both stator assemblies, eliminating the need for separate rotor back irons and simplifying the overall rotor structure.
Solution Approach 2:
The integrated rotor magnet serves multiple purposes: generating magnetic flux, providing magnetic return paths to both stator assemblies, and eliminating the need for separate rotor back irons. This multi-functional design reduces structural complexity while maintaining effective magnetic flux management.
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 design enhances power density, efficiency, and specific power, enabling the electric machine to operate at higher speeds with reduced mass and volume, thereby achieving a higher power-to-weight ratio and improved performance.
Implementation Method 1
The rotor magnet of the rotor disk spaced from the stator assembly along the axial direction of the electric machine to generate an axial flux across an airgap
Implementation Method 2
The rotor magnets are a continuous magnet embedded within the rotor disk and extending along the circumferential direction, wherein the continuous magnet comprises alternating polarity portions arranged along the circumferential direction
Data Source
Figure 1~2
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Figure 4
AI summary
An electric machine is provided which includes a rotor disk extending along a radial direction and a having a rotor magnet embedded within the rotor disk. The electric machine further includes a stator assembly in axial or radial magnetic flux communication with the rotor magnets to generate a torque.