Double-Layer IPM Rotor Structure for Torque and Centrifugal Stress
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Solution Overview
Problem
Existing double-layer interior permanent-magnet rotary electric machines face challenges in balancing torque performance and structural strength due to centrifugal stress, which can lead to deformation and fracture, especially when outer bridges are open or hollowed, affecting torque characteristics at medium to high speeds.
Innovation Solution
A double-layer interior permanent-magnet rotor design with specific accommodation holes and magnets arranged in a configuration where the inner-side open angle is equal to or higher than the outer-side open angle, ensuring that inner-side accommodation holes communicate with the outer side of the rotor core, while maintaining structural integrity and torque performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If bridges on the outer circumferential side are opened to reduce leakage flux, then torque characteristics are improved, but centrifugal stress exceeds mechanical strength causing deformation and fracture
Solution Approach 1:
The patent applies local quality by differentiating the treatment of bridges between the first and second layers. The first layer maintains solid bridges for structural strength, while the second layer has hollowed bridges for flux reduction. This localized differentiation allows each layer to serve its specific function without compromising overall rotor integrity.
2Stability of the object's composition
If magnets in the second layer are made closer together with smaller open angle, then deformation is reduced, but inner ends of magnets move inward making it impossible to cut out core for lightening
Solution Approach 1:
The patent segments the rotor structure into two distinct layers with different bridge configurations. The first layer has solid bridges for structural support, while the second layer has hollowed bridges that enable core cutout for lightening. This segmentation allows simultaneous optimization of structural stability and weight reduction.
3Weight of moving object
If outer bridges are hollowed to reduce weight, then rotor is lightened, but centrifugal stress exceeds strength criterion value in some parts
Solution Approach 1:
The patent resolves the contradiction by adding a dimensional distinction between layers. Instead of uniformly hollowing all bridges, it hollows bridges only in the second layer while maintaining solid bridges in the first layer. This dimensional differentiation allows weight reduction while preserving structural reliability in critical areas.
4Stress or pressure
If open angle of magnets in second layer is made small, then centrifugal stress is reduced, but torque in medium-speed to high-speed range decreases
Solution Approach 1:
The patent segments the flux barrier function between layers: the first layer with solid bridges provides structural support and handles centrifugal stress, while the second layer with hollowed bridges provides flux barrier function for torque optimization. This segmentation allows independent optimization of stress management and torque characteristics.
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 effectively reduces centrifugal stress to within structural limits, maintaining torque performance across speed ranges while allowing for rotor lightening, thus addressing the balance between strength and torque.
Implementation Method 1
centrifugal force generated by high-speed rotation
Data Source
AI summary
According to embodiments, a two-layer magnet-embedded rotor includes: a rotor shaft; a rotor core including first and second outer side accommodation holes and first and second inner side accommodation holes; first and second outer side magnets; and first and second inner side magnets. The first inner side accommodation hole and the second inner side accommodation hole communicate with the outer side of the outer circumference. A value of an inner-side open angle Θb1 at which radially outer side walls and of the inner side accommodation holes open toward a radially outer side is from a prescribed value to a value of an outer-side open angle Θa at which radially outer side walls of the outer side accommodation holes open toward the radially outer side.