Electric Motor Rotor With Stacked Laminations For Noise Reduction
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Solution Overview
Problem
Conventional permanent-magnet electric motors generate significant noise and vibrations, are costly due to rare earth element usage, and have performance limitations with ferrite magnets, making them less suitable for residential and commercial applications and hindering market penetration.
Innovation Solution
A rotor design with a pack of ferromagnetic laminations and radially arranged parallelepiped-shaped permanent magnets, magnetized perpendicular to the rotor radius, featuring rotated poles and inclined grooves to reduce noise and vibrations, allowing for cost-effective production and use of conventional control algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ferrite magnets are used instead of rare earth elements, then cost is reduced, but performance (residual induction and intrinsic coercive force) decreases to one third of rare earth values
Solution Approach 1:
The rotor is segmented into multiple laminations (at least two) stacked along the rotation axis, with each lamination containing permanent magnets arranged in alternating polarity patterns. This segmentation allows the use of ferrite magnets while maintaining performance through cumulative magnetic effects across multiple layers.
Solution Approach 2:
The invention transitions from a single-plane magnet arrangement to a three-dimensional stacked lamination structure. By arranging magnets in alternating patterns across multiple laminations separated by non-magnetic spacers, the design exploits the third dimension (axial direction) to achieve performance equivalence with rare earth magnets using cheaper ferrite materials.
2Ease of manufacture
If IPM configuration is used to accommodate greater magnet volume, then cost is contained, but noise and mechanical vibrations increase
Solution Approach 1:
Each lamination features an asymmetric magnet arrangement with a first set of magnets having north-south polarity and a second set with south-north polarity, creating a specific alternating pattern. This asymmetric configuration, combined with the multi-lamination structure, reduces magnetic unbalance and minimizes noise and vibrations compared to conventional IPM designs.
Solution Approach 2:
Non-magnetic spacers are introduced between adjacent laminations to act as intermediaries that decouple the magnetic fields of individual laminations. This reduces magnetic interaction and unbalance forces between layers, thereby minimizing noise and vibrations while maintaining the cost benefits of ferrite magnets.
3Quantity of substance
If IPM configuration is used, then magnet volume is increased, but control complexity increases requiring different algorithms
Solution Approach 1:
The multi-lamination rotor design with alternating magnet polarity is compatible with conventional SPM control algorithms, providing universality. The structure achieves IPM-level magnet volume while maintaining SPM-level control simplicity, allowing the same control algorithm to be used across different motor configurations without requiring complex calibration or specialized control strategies.
4Ease of operation
If SPM configuration is used, then control is simplified, but magnet volume is reduced limiting performance
Solution Approach 1:
The invention nests multiple laminations with permanent magnets inside the rotor structure, with each lamination containing sets of magnets arranged in alternating polarity. This nested multi-layer configuration increases the total magnet volume and performance capability while maintaining the external rotor dimensions, effectively packing more magnetic material without increasing overall motor size.
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 achieves superior acoustic comfort, reduced costs, and comparable performance to rare earth-based motors, enabling broader market adoption, including residential and commercial sectors, while minimizing noise and vibrations.
Implementation Method 1
permanent magnets, which are inside the rotor, arranged radially with respect to a rotation axis... magnetized along a direction that is perpendicular to a radius of the rotor
Implementation Method 2
rotor of an electric motor with permanent magnets... stator, in the slots of which a three-phase winding is accommodated
Implementation Method 3
pack of laminations made of ferromagnetic material
Data Source
AI summary
A rotor of an electric motor with permanent magnets includes a pack of laminations made of ferromagnetic material with slots for the permanent magnets which are arranged radially with respect to the rotation axis and are extended parallel thereto. The permanent magnets are magnetized along a direction that is perpendicular to the radius of the rotor. Each lamination of the lamination pack further includes poles between the permanent magnets that are rotated in a given direction and by a given angle with respect to the corresponding poles of the adjacent laminations.