Vehicular Rotor Magnet Segmentation for Torque Pulsation Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Torque pulsations in rotating electric machines used in automotive applications cause noise and vibration, affecting driver and passenger comfort, and existing technologies have not effectively minimized both magnetic and reluctance torque pulsations.
Innovation Solution
The use of permanent magnets with magnet pieces formed in a substantially rectangular parallelepiped shape and trapezoidal shapes, along with varying lengths and positions, to reduce torque pulsations by optimizing the magnetic flux distribution and reluctance torque generation, and the adoption of a concentrated winding system and fractional pitch winding to further minimize torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor adopts a structure that assures lower magnetic resistance at auxiliary magnetic poles to increase reluctance torque, then the output torque is improved and magnet mass is reduced, but reluctance torque pulsations occur
Solution Approach 1:
The rotor core is segmented into multiple yokes arranged circumferentially, with each yoke containing auxiliary magnetic poles. This segmentation allows independent optimization of magnetic resistance in each sector, enabling the reduction of reluctance torque pulsations while maintaining high output torque through proper configuration of the segmented structures.
Solution Approach 2:
The auxiliary magnetic poles are designed with asymmetric magnetic resistance characteristics relative to the q-axis magnetic flux. By creating controlled asymmetry in the magnetic circuit path through different air gap lengths and yoke configurations, the patent optimizes reluctance torque generation while balancing the pulsation effects across different rotor positions.
2Power
If permanent magnets are embedded in the rotor core to provide strong magnetic energy, then the torque output is improved, but torque pulsations caused by cogging torque occur
Solution Approach 1:
Different regions of the rotor core are given different magnetic properties through the segmentation into multiple yokes. Each yoke can be independently designed with specific magnetic resistance characteristics, allowing local optimization to reduce cogging torque effects while maintaining strong magnetic energy from the embedded permanent magnets in critical torque-generating regions.
Solution Approach 2:
The patent introduces a new dimensional approach by arranging multiple yokes circumferentially around the rotor core, creating a multi-layered magnetic circuit structure. This circumferential segmentation adds a spatial dimension to torque generation, allowing the superposition of magnetic fields from multiple yokes to smooth out torque pulsations while maintaining high overall torque output.
3Object-generated harmful factors
If the position of permanent magnets is offset along the circumferential direction to reduce torque pulsations, then magnetic torque pulsations are reduced, but the structure does not address reluctance torque pulsations
Solution Approach 1:
The segmented yoke structure serves multiple functions simultaneously: it offsets permanent magnets to reduce magnetic torque pulsations, provides auxiliary magnetic poles for reluctance torque generation, and creates asymmetric magnetic resistance paths to balance reluctance torque pulsations. This multi-functional design addresses both magnetic and reluctance torque pulsations within a single integrated structure.
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 approach significantly reduces torque pulsations, noise, and vibration, enhancing driver and passenger comfort while improving the efficiency and productivity of the rotating electric machine, allowing for a more reliable and compact design suitable for electric vehicles.
Implementation Method 1
a rotor core (252) and permanent magnets (254, 255) embedded in the rotor core
Implementation Method 2
d-axis magnetic flux (296) and magnetic torque
Implementation Method 3
auxiliary magnetic poles, through which a q-axis magnetic flux passes... increased the reluctance torque
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A rotating electric machine for vehicular use having n types of magnet pieces includes: a stator (230) that includes a stator core (232) and a stator winding (238) wound at the stator core (232); and a rotor (250) that is rotatably disposed relative to the stator (230) and includes a rotor core (252) formed by laminating a plurality of electromagnetic steel sheets with a plurality of magnet insertion holes (272) formed therein and includes a plurality of permanent magnets (254, 255) each held in each of the plurality of magnet insertion holes (272) to form a magnetic pole. Each of the plurality of permanent magnets (254, 255) extends along a rotor axis and is formed in a shape assuming at least two different lengths along a circumference of the rotor.