Segmented Rotor Magnet Layout for Low-Ripple EV Reluctance Motors
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Solution Overview
Problem
Existing electric vehicle motors face issues of low efficiency, high noise, and susceptibility to demagnetization due to the use of ferrite permanent magnets, which are also non-renewable and expensive.
Innovation Solution
A rotor structure with a magnetic steel slot group arrangement that allows for more permanent magnets in a unit volume, enhancing q-axis inductance, reducing torque ripples, and improving anti-demagnetization ability by optimizing the placement and shape of outer and inner layer permanent magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If ferrite permanent magnets are used in the motor, then the production cost is reduced, but the motor efficiency is low and the motor is easily demagnetized
Solution Approach 1:
The rotor is divided into multiple magnetic steel slots (first, second, third slots) with permanent magnets arranged in specific segments. This segmentation allows for optimized magnetic flux distribution and enhanced anti-demagnetization capability while maintaining efficiency
Solution Approach 2:
Different regions of the rotor are designed with different magnetic steel slot configurations. The first, second and third magnetic steel slots have different geometries and positions, creating local quality variations that optimize both efficiency and demagnetization resistance in different areas
2Productivity
If more permanent magnets are added to increase power density, then the motor efficiency improves, but the rotor volume and complexity increase
Solution Approach 1:
Multiple magnetic steel slots are nested within the rotor structure in a compact arrangement. The first, second and third slots are positioned to maximize space utilization, allowing more permanent magnets to be accommodated in a limited rotor volume without excessive expansion
Solution Approach 2:
The magnetic steel slots are arranged in different spatial dimensions and orientations within the rotor. By utilizing three-dimensional space efficiently and arranging slots at different angular positions, the design achieves high power density without proportionally increasing rotor volume
3Object-generated harmful factors
If the magnetic steel slot configuration is optimized to reduce torque ripples, then the vibrations and noise are reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The magnetic steel slots are designed with asymmetric geometries and different angular positions. The first, second and third slots have intentionally different configurations that create balanced magnetic flux distribution, reducing torque ripples and associated vibrations and noise
Solution Approach 2:
The magnetic steel slots are pre-configured with specific geometries and positions during the design and manufacturing phase to preemptively balance the magnetic flux distribution. This preliminary optimization of slot configuration reduces torque ripples before the motor operates, thereby reducing vibrations and noise
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 motor efficiency, reduces vibrations and noise, and enhances the anti-demagnetization capability of the motor, achieving higher power density and reliability.
Implementation Method 1
a first magnetic barrier bridge is formed between the second end of the first slot and the outer edge of the rotor body
Implementation Method 2
outer layer permanent magnet arranged in the magnetic steel slot segment
Implementation Method 3
A rotor structure includes a rotor body and outer layer permanent magnet arranged in the magnetic steel slot segment
Data Source
Figure 1
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AI summary
A rotor structure, a permanent magnet auxiliary synchronous reluctance motor and an electric vehicle, the rotor structure includes a rotor body and an outer layer permanent magnet. The rotor body is provided with a magnetic steel slot group. The magnetic steel slot group includes an outer layer magnetic steel slot. The outer layer magnetic steel slot includes a plurality of magnetic steel slot segments. At least two of the plurality of magnetic steel slot segments are arranged in a radial direction of the rotor body and are disposed oppositely at both sides of a direct axis of the rotor body. The outer layer permanent magnet is arranged in the magnetic steel slot segment, a length of the outer layer permanent magnet disposed in the two oppositely arranged magnetic steel slot segments is L, and a maximum distance between the two oppositely arranged magnetic steel slot segments is C, where 0.8×C≤L. By means of arranging the outer layer magnetic steel slot of the magnetic steel slot group on the rotor body, more permanent magnets are placed in a unit volume of the rotor, thereby generating a larger permanent magnet torque, improving a q-axis inductance of the motor, increasing efficiency of the motor, reducing torque ripples of the motor, reducing vibrations and noises of the motor, and improving demagnetization ability of the motor.