Rotary Electric Machine Rotor Segmentation for Torque Pulsation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for reducing torque pulsation in rotary electric machines have difficulty separating the reduction of cogging torque from the reduction of torque pulsation due to stator current, often affecting both simultaneously, making it challenging to effectively address both issues.
Innovation Solution
The rotary electric machine is designed with a rotor core divided into multiple division cores, featuring magnetic air gaps and magnet auxiliary salient poles, where the circumferential positions of magnets are constant, and the phases of torque pulsations generated by different core groups are shifted, allowing for independent reduction of torque pulsation due to stator current with minimal impact on cogging torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional methods are used to reduce torque pulsation, then torque pulsation due to stator current is reduced, but cogging torque is also affected and cannot be independently optimized
Solution Approach 1:
The rotor core is divided into multiple division cores (first division core, second division core, etc.) with different numbers of magnetic poles. Each division core can independently generate torque pulsation with different characteristics, allowing the total torque pulsation to be reduced through phase shifting while maintaining independent optimization of cogging torque reduction
Solution Approach 2:
Different division cores are designed with different local magnetic pole configurations (different numbers of poles). The first division core has a different number of magnetic poles compared to the second division core, creating locally different magnetic field distributions that result in phase-shifted torque pulsations when the same stator current is applied
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 effectively reduces torque pulsation caused by stator current while maintaining low influence on cogging torque, leading to improved ride quality, reduced vibration, and noise in electric vehicles, and allows for efficient operation across a wide range of rotation speeds.
Implementation Method 1
a magnetic flux generated from a permanent magnet provided in a rotor to pass through a stator and then to return to the rotor again
Implementation Method 2
The occurrence of torque pulsation in a rotary electric machine is caused by the cogging torque due to a magnetic circuit
Implementation Method 3
a rotating magnetic flux generated by a current of the stator
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A rotary electric machine includes a stator (230) having stator windings (238; 338); and a rotor (250) rotatably disposed in the stator (230), said rotor (250) having a rotor core (252) provided with a plurality of magnets (254) and a plurality of magnetic auxiliary salient poles (259) formed between poles of the magnets (254). In this rotary electric machine: a magnetic air gap (258) is provided in an axial direction of the rotor (250) in a position shifted in a circumferential direction from a q axis passing through a center of the magnetic auxiliary salient pole (259) within the magnetic auxiliary salient pole (259); and an amount of shifting the magnetic air gap (258) from the q axis in the circumferential direction differs according to a position of the magnetic air gap (257) in the axial direction so as to cancel torque pulsation in energization caused due to the magnetic air gap (258).