Permanent-Magnet Rotor Layout for Higher Torque Density
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Solution Overview
Problem
Existing rotary electric machines face challenges in improving magnetic performance, torque density, and reducing manufacturing and assembly costs, particularly in permanent-magnet rotors.
Innovation Solution
A rotor design featuring a rotor body with laminations stacked on one another, incorporating recesses arranged in two rows, where the first row forms a U shape with a central and two side recesses, and the second row is V-shaped, with notches extending from side recesses to central recesses, optimizing magnet placement and magnetic flux path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of permanent magnets in the rotor body is increased to improve power density and torque, then the magnetic performance and torque density are improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The rotor body is segmented into multiple stacks of laminations, with recesses arranged in two rows (first row with three recesses in U-shape, second row with V-shaped recesses). This segmentation allows increased number of permanent magnets while maintaining manageable assembly complexity through modular stack construction
Solution Approach 2:
The recesses are arranged in two rows along the axial direction of the rotor, transitioning from a single-row planar arrangement to a two-row three-dimensional configuration. This dimensional change increases magnet capacity without proportionally increasing radial or circumferential complexity
2Power
If the recesses are arranged in two rows with optimized geometry to improve magnetic performance, then the torque density increases, but the manufacturing precision requirements increase
Solution Approach 1:
Different regions of the rotor have locally optimized recess geometries: the first row has three recesses (central and two side recesses) with specific length ratios (central recess length = +/−20% of side recess length), while the second row has V-shaped recesses. These localized geometric variations optimize magnetic performance without requiring ultra-precise manufacturing across the entire rotor
Solution Approach 2:
The recess dimensions are defined with specific parameter relationships (length ratios, angular positions) that optimize magnetic circuit performance. The central recess length is set at +/−20% of side recess length, and notches are positioned at specific angles, providing clear manufacturing parameters that balance performance optimization with manufacturability
3Loss of energy
If the recess geometry is optimized with notches extending toward the central recess to reduce leakage flux, then the magnetic circuit efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
Notches are pre-formed in the side recesses during the lamination manufacturing process, extending toward the central recess at defined angles. This preliminary action of creating notches in advance reduces leakage flux paths without requiring complex post-assembly operations
Solution Approach 2:
The notches in the side recesses are designed with curved or angled geometries that guide magnetic flux more efficiently toward the central recess, reducing leakage. The curved transitions in the notch geometry reduce flux discontinuities while maintaining manufacturability through standard forming processes
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 the number of magnets per rotor space, enhancing power density and torque, while reducing leakage flux and manufacturing complexity, thus improving reluctance torque and mechanical strength.
Implementation Method 1
permanent magnets defining poles of the rotor
Implementation Method 2
permanent magnets of various geometric shapes... defining poles of the rotor
Implementation Method 3
rotor body comprising laminations stacked on one another
Data Source
AI summary
Rotor (30) for a rotary electric machine, comprising a rotor body (33) comprising metal sheets stacked one on top of the other, the rotor body (33) comprising a plurality of housings (10) for receiving one or more permanent magnets defining poles of the rotor, the housings of a pole being arranged in at least one first (11) and one second (12) row of housings, the first row of housings comprising three U-shaped housings, with a central housing and two side housings, a length (L2) of a larger rectangle enclosed in the central housing being equal to +/−20% of the length (L1) of the largest rectangle enclosed in a side housing, at least one of the side housings, in particular the two side housings of the first row, comprising a recess (15) which extends from the side housing to the central housing.