Hybrid Rotor Lamination Layout for Low-Torque-Ripple Synchronous Machines
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Solution Overview
Problem
Synchronous electric machines with permanent magnet rotors are susceptible to torque ripples and excess heat, affecting their overall performance.
Innovation Solution
A hybrid rotor design incorporating laminations with both permanent and non-permanent magnet subsets, featuring through-holes and pockets for permanent magnets, which minimizes torque ripples and optimizes thermal performance by distributing magnetic and reluctance torques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a rotor having permanent magnets is used, then the synchronous electric machine can generate magnetic torque, but the rotor becomes susceptible to torque ripples and excess heat
Solution Approach 1:
The rotor is segmented into multiple laminations stacked axially, with each lamination containing permanent magnets in specific pockets. This segmentation allows the rotor to distribute magnetic torque across multiple layers, reducing the concentration of torque ripples in any single layer and improving overall torque smoothness.
Solution Approach 2:
Different regions of the rotor are given different properties: permanent magnets are placed in specific pockets of certain laminations to generate magnetic torque where needed, while other laminations are designed without permanent magnets to provide reluctance torque and reduce torque ripples. This local differentiation optimizes both torque generation and ripple reduction.
2Power
If a rotor having permanent magnets is used, then the synchronous electric machine can generate magnetic torque, but the rotor experiences excess heat affecting thermal performance
Solution Approach 1:
The rotor is divided into multiple laminations with permanent magnets positioned in specific pockets of selected laminations. This segmentation distributes the heat-generating permanent magnets across multiple layers, allowing better thermal management and heat dissipation pathways, thereby improving overall thermal performance while maintaining magnetic torque generation.
3Power
If permanent magnets are used in the rotor, then magnetic torque is generated, but the reliance on permanent magnets influences overall machine performance negatively
Solution Approach 1:
The rotor design merges two torque generation mechanisms: magnetic torque from permanent magnets and reluctance torque from the rotor's magnetic anisotropy. By combining these two mechanisms in a hybrid configuration, the system reduces dependency on permanent magnets alone while maintaining or enhancing overall torque performance and reducing negative performance influences.
Solution Approach 2:
The rotor employs a composite structure combining laminations with permanent magnets and laminations without permanent magnets. This composite design creates a hybrid rotor that leverages both permanent magnet and reluctance torque mechanisms, reducing the negative impacts of permanent magnet dependency while maintaining effective torque generation.
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 hybrid rotor design maintains torque performance while reducing torque ripples and heat-related issues, enhancing the overall efficiency and reliability of the synchronous electric machine.
Implementation Method 1
The permanent magnets are operable for interacting magnetically with the RMF
Implementation Method 2
A synchronous electric machine includes a stator and a hybrid rotor. The stator includes a plurality of conductive windings configured for carrying alternating currents for generating a rotating magnetic field (RMF)
Implementation Method 3
A non-permanent magnet subset of the laminations includes one or more through-holes configured for limiting torque ripple
Data Source
AI summary
Synchronous electric machines including a stator having a plurality of conductive windings configured for carrying alternating currents for generating a rotating magnetic field (RMF), and a hybrid rotor configured for rotating within the stator according to a torque induced by the RMF. The hybrid rotor includes a plurality of laminations stacked together axially. The laminations include a non-permanent magnet subset of the laminations having one or more through-holes configured for limiting torque ripples. The laminations include a permanent magnet subset of the laminations having one or more pockets, with the pockets each removably holding one or more permanent magnets. The permanent magnets are operable for interacting magnetically with the RMF.