Multi-Layer Permanent Magnet Rotor for Lower Torque Ripple
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Solution Overview
Problem
Existing electric machines with conventional permanent magnet arrangements face limitations in magnetic flux, engine-speed strength, torque ripple, and magnetic losses, which hinder high performance and efficiency.
Innovation Solution
A multi-layered arrangement of permanent magnets with a C-minus configuration, featuring larger magnets and optimized connecting portions, reduces torque ripple and magnetic losses while enhancing magnetic flux and engine-speed strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional permanent magnet arrangements are used, then the structure is simple, but the magnetic flux and engine-speed strength are limited
Solution Approach 1:
The rotor pole is segmented into multiple layers (first radially inner layer, second radially inner layer, and radially outer layer) with permanent magnets arranged in different configurations in each layer. This segmentation allows optimization of magnetic flux distribution and engine-speed strength independently in each layer, resolving the contradiction between improving power output and maintaining structural simplicity.
Solution Approach 2:
The invention transitions from a conventional single-layer or two-layer arrangement to a multi-layered three-dimensional configuration with magnets positioned at different radial depths and angular positions. The third radial dimension enables independent optimization of each layer's contribution to magnetic flux and torque characteristics, achieving higher power density without excessive complexity.
2Adaptability or versatility
If smaller permanent magnets are used to achieve multi-layered arrangement, then the arrangement flexibility increases, but the demagnetization strength decreases
Solution Approach 1:
By utilizing the radial dimension to create multiple layers, the invention achieves arrangement flexibility without reducing magnet size in the tangential direction. Larger magnets can be used in each layer while maintaining the multi-layered configuration, thus preserving demagnetization strength while gaining arrangement versatility.
Solution Approach 2:
Different layers are designed with different magnet arrangements optimized for their specific functions: the radially outer layer with tangential magnets optimizes for demagnetization strength and torque, while inner layers can be optimized for magnetic flux generation. This local optimization allows each layer to use appropriately sized magnets for its purpose.
3Object-generated harmful factors
If conventional magnet arrangements are used, then the design is simple, but torque ripple and magnetic losses are high
Solution Approach 1:
The rotor pole is segmented into multiple layers with distinct pocket arrangements (C-shaped in inner layers, U-shaped in outer layer) and connecting portions at different radial positions. This segmentation allows each layer to contribute differently to torque production, smoothing out torque ripple through complementary magnetic field interactions while managing complexity through modular design.
Solution Approach 2:
The rotor employs a composite magnetic structure combining different magnet arrangements in series and parallel configurations across multiple layers. This composite approach creates a synergistic effect where the combined magnetic fields reduce harmonic content and torque ripple, while the modular composite structure manages design complexity.
4Strength
If larger permanent magnets are used, then the demagnetization strength increases, but the arrangement flexibility decreases
Solution Approach 1:
The invention resolves this contradiction by exploiting the radial dimension to create multiple layers, allowing large magnets to be used in each layer while achieving arrangement flexibility through the multi-layered configuration. The radial stacking enables independent positioning and sizing of magnets in each layer without compromising overall arrangement versatility.
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 solution increases magnetic flux, tolerates higher rotor temperatures, and achieves high torques and powers with reduced losses, leading to improved continuous performance and cost-effectiveness.
Implementation Method 1
The multi-layered arrangement of permanent magnets, which enables an increase of the magnetic rotor flux
Implementation Method 2
This results in a higher demagnetization strength, as a result of which higher rotor temperatures can be tolerated
Data Source
AI summary
The present invention relates to a rotor (1) of an electric machine (10), comprising a rotor body (2) which can be rotated about a rotor axis (100), has an outer circumference (8) and a plurality of rotor poles (5) and is formed by a stack of laminations, each rotor pole (5) having a central pole axis (101) and an arrangement of permanent magnets (4) arranged in pockets (6, 7) of the rotor body (2), in particular the stack of laminations, the arrangement of permanent magnets (4) comprising two radially spaced layers (3i, 3a) having permanent magnets (4), the radially inner layer (3i) having two inner pockets (6) arranged symmetrically with respect to the central pole axis (101) and an inner connecting portion (9i) between the two inner pockets (6), and the radially outer layer (3a) having an outer pocket (7) arranged symmetrically with respect to the central pole axis (101), characterized in that the inner connecting portion (9i) is a single connecting portion arranged symmetrically with respect to the central pole axis (101), in that two additional pockets (12) which act as a flow barrier and are arranged symmetrically with respect to the central pole axis (101) are provided between the outer circumference (8) of the rotor body (2) and the outer pocket (7), and in that each additional pocket (12) forms a first outer connecting portion (9a) between the additional pocket (12) and the outer pocket (7).