Synchronous Motor Rotor with Elliptical Cavities and Variable Bar Width
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Solution Overview
Problem
Synchronous drive motors for electric vehicles face challenges in maximizing both synchronous and reluctance torque while minimizing flux harmonic and leakage losses, which are affected by centrifugal forces and magnetic flux distribution.
Innovation Solution
The rotor design features multiple U-shaped magnetic layers with ellipsically arranged cavities filled with permanent magnetic material, where the central points of ellipses are concentric and the ratio of their axes is controlled to optimize magnetic flux paths, and narrow outer bars are used to reduce leakage and enhance rotational stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the outer bars are made narrow to reduce flux leakage, then flux leakage losses are reduced, but the rotor deforms due to high centrifugal forces on the magnets
Solution Approach 1:
The patent applies parameter changes by varying the width of the outer bars across different magnetic layers. Specifically, the outer bars in the outermost magnetic layer are made wider than those in inner magnetic layers. This gradual parameter change allows the rotor to withstand centrifugal forces while minimizing flux leakage losses, as the wider outer bars provide structural support without excessive width that would cause leakage.
Solution Approach 2:
The patent implements local quality by making the outer bars width-dependent on their radial position. The outer bars in the outermost magnetic layer have a different width compared to outer bars in inner magnetic layers. This localized variation in bar width optimizes the balance between mechanical strength (to prevent deformation) and magnetic performance (to reduce flux leakage) at different radial locations of the rotor.
2Power
If the number of cavities per magnetic layer is increased to improve torque, then eddy-current losses increase, but dividing into more smaller cavities reduces losses and improves efficiency
Solution Approach 1:
The patent applies segmentation by dividing each magnetic layer into multiple cavities rather than using fewer larger cavities. Each magnetic layer contains at least two cavities filled with permanent magnetic material, with the outermost layer having at least one cavity. This segmentation increases the total magnetic surface area for torque generation while reducing eddy-current losses by creating more, smaller cavities that interrupt eddy current paths.
Solution Approach 2:
The patent utilizes the radial dimension by arranging cavities at different radial positions within each magnetic layer. The cavities are positioned to extend in the radial direction, with inner cavities filled with permanent magnets and outer cavities serving as flux barriers. This dimensional arrangement optimizes both torque production and loss reduction by exploiting the radial geometry of the rotor.
3Stability of the object's composition
If the outer bars are made wider to prevent rotor deformation, then structural stability is improved, but flux leakage increases and efficiency decreases
Solution Approach 1:
The patent applies parameter changes by varying the width of the outer bars across different magnetic layers. Specifically, the outer bars in the outermost magnetic layer are made wider than those in inner magnetic layers. This gradual parameter change allows the rotor to withstand centrifugal forces while minimizing flux leakage losses, as the wider outer bars provide structural support without excessive width that would cause leakage.
Solution Approach 2:
The patent implements local quality by making the outer bars width-dependent on their radial position. The outer bars in the outermost magnetic layer have a different width compared to outer bars in inner magnetic layers. This localized variation in bar width optimizes the balance between mechanical strength (to prevent deformation) and magnetic performance (to reduce flux leakage) at different radial locations of the rotor.
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 increases torque efficiency by reducing eddy-current losses and maintaining rotational speed stability, while minimizing flux leakage and torque ripple, thus improving the overall performance and efficiency of the synchronous drive motor.
Implementation Method 1
each cavity is filled with permanent magnetic material
Implementation Method 2
synchronous drive motor of an electrically driven motor vehicle
Implementation Method 3
due to the high centrifugal forces acting on the magnets in the cavities
Implementation Method 4
route the magnetic flux from the rotor and into the stator radially on the respective pole
Implementation Method 5
Leakage losses, which reduce the efficiency, result primarily along the radially outer edge of the rotor
Data Source
AI summary
The invention relates to a rotor for a synchronous drive motor of an electrically driven motor vehicle having several rotor poles, wherein each rotor pole has at least three magnetic layers arranged radially one after the other with cavities, wherein an outermost magnetic layer includes at least one cavity filled with permanent magnetic material and each further magnetic layer includes at least two cavities filled with permanent magnetic material, furthermore each magnetic layer has an extension of a section of an ellipse, furthermore the central points of all ellipses lie within the smallest ellipse of the outer magnetic layer, wherein each cavity belonging to one of the at least three magnetic layers defines an interface in a radial plane, and each of these interfaces of a magnetic layer of the corresponding ellipse is divided into two partial interfaces, wherein bars made of the rotor material are formed in the second and every other magnetic layer between the cavities, and these bars, at the narrowest point, are at least twice as wide as the respective outer bars of the same magnetic layer.