Rotor Permanent Magnet Segmentation for Centrifugal Stress
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Solution Overview
Problem
Existing segmented permanent magnet electric machine rotors face stress issues due to centrifugal forces at high speeds, particularly when magnets are imbalanced, leading to reduced magnetic power and complex manufacturing processes.
Innovation Solution
The rotor design incorporates parallelepipedic permanent magnets with beveled angles and trapezoidal ends, allowing for reduced mass and force distribution, optimized magnetic volume, and simplified manufacturing through radial retention lips and pads, along with optional springs and cooling circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a radial reinforcing plate is used to support permanent magnets in notches, then rotor strength is improved, but magnet volume is reduced and manufacturing complexity increases
Solution Approach 1:
The rotor body is segmented into multiple notches that receive permanent magnets, allowing the magnetic mass to be divided into functional segments. This segmentation enables the magnets to be positioned strategically to provide reinforcement without requiring a continuous radial plate, thereby preserving magnet volume while achieving structural strength.
Solution Approach 2:
The structural reinforcement function and magnetic function are merged into a single integrated design. The permanent magnets themselves serve dual purposes: generating magnetic field and providing structural reinforcement to the rotor body, eliminating the need for separate reinforcing plates that would occupy space.
2Strength
If a radial reinforcing plate is used to support permanent magnets in notches, then rotor strength is improved, but manufacturing complexity increases
Solution Approach 1:
The rotor body structure is designed to serve multiple functions simultaneously: it provides the magnetic circuit path, contains the notches for magnets, and provides structural reinforcement through the arrangement of magnets and notches themselves. This multi-functionality eliminates the need for separate reinforcing components, simplifying manufacturing.
3Power
If permanent magnets are positioned in imbalance due to assembly games, then magnetic power is maintained, but stress on rotor body increases at high speeds
Solution Approach 1:
The rotor design incorporates local variations in notch geometry and magnet positioning to accommodate assembly tolerances. The notches are designed with specific geometric characteristics that distribute centrifugal forces more evenly across the rotor body, reducing stress concentrations that would arise from magnet imbalance while preserving magnetic performance.
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 reduces stress on the rotor, enhances magnetic performance, and simplifies the manufacturing process, enabling efficient operation at high speeds while maintaining magnetic power.
Implementation Method 1
The rotor comprises a body formed by a stacking sheet leaves held in the form of a package by means of a suitable fixing system, such as rivets crossing axially the rotor on the other hand. The rotor comprises poles formed for example by permanent magnets housed in slotted notches in the magnetic mass of the rotor.
Implementation Method 2
These stress areas are caused by the centrifugal forces applied on the rotor body by the magnets positioned inside the notches, in particular when the magnets are positioned in imbalance due to the assembly games.
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention mainly relates to a rotor (10) of an electrical rotating machine, comprising a body (11) and at least one slot (16) made in said body (11). Said slot (16) extends from one face to the other of said body (11) of said rotor (10), and at least two permanent magnets (17) are inserted in said slot (16).