Segmented Motor Rotor Structure for High-Speed Eddy Loss Reduction
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Solution Overview
Problem
Conventional axial flux permanent magnet machines face challenges with structural strength at high rotation speeds due to centrifugal forces and increased eddy current losses, leading to reduced efficiency and heat issues.
Innovation Solution
The rotor core is reinforced in both axial and radial directions by adding magnetic steels and SMC sheets, with a redesigned rotor yoke structure to enhance magnetic circuit efficiency and torque density, and incorporating a rotor pressing plate to fasten the magnetic steels and sheets in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the rotor operates at high rotation speed, then the torque density and efficiency are improved, but the structural strength deteriorates due to large centrifugal force
Solution Approach 1:
The rotor core is divided into multiple segments with protruding components that create grooves for magnetic steel insertion. This segmentation allows for better stress distribution and reduces centrifugal force effects on the overall structure, enabling high-speed operation while maintaining structural integrity
Solution Approach 2:
The rotor employs composite construction combining rotor core, magnetic steel pieces, and rotor pressing plate. This composite structure provides both the magnetic properties needed for torque generation and the mechanical strength required to withstand high-speed centrifugal forces
2Productivity
If the rotor operates at high rotation speed, then the torque density is improved, but eddy current loss increases causing rotor heat and lower efficiency
Solution Approach 1:
The magnetic steel is divided into multiple separate pieces inserted into grooves rather than using a single continuous piece. This segmentation interrupts eddy current paths, significantly reducing eddy current losses while maintaining magnetic performance for high-speed operation
Solution Approach 2:
The rotor pressing plate acts as an intermediary component that secures magnetic steel pieces in grooves. This pressing plate provides mechanical retention while allowing the segmented magnetic steel structure to function effectively at high speeds with reduced eddy current losses
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 improves structural strength, reduces eddy current losses, and enhances efficiency by increasing torque density and reducing heat generation, making it suitable for high-speed operation.
Implementation Method 1
there is large centrifugal force due to a large outer diameter of a rotor disk that moves at a high speed
Implementation Method 2
a greater electromagnetic reluctance torque, so that a torque density is further improved
Implementation Method 3
there is obviously a greater eddy current loss of a conventional surface-mounted permanent magnet rotor structure, causing the rotor to heat up and have lower efficiency
Data Source
Figure 1
Figure 2~3
Figure 4(a)
AI summary
This application relates to the field of motor technologies, and provides a motor rotor, a drive motor, and an electric vehicle. In the motor rotor, a rotor core with at least two protruding components is designed. At least two magnetic steels and at least two sheets are disposed in grooves between the at least two protruding components and then coupled to the rotor core with a rotor pressing plate, to fasten the plurality of magnetic steels and the plurality of sheets in the grooves on the rotor core, thereby ensuring reliability of the motor rotor in an axial direction. In addition, one SMC sheet is stacked on each of the magnetic steels, so that an eddy current loss of a permanent magnet can be effectively reduced. Each of the magnetic steels is disposed in a groove between protruding components, and the SMC sheet is added, so that a saliency ratio is increased, a reluctance torque ratio is increased, and a quantity of magnetic steels for use is reduced.