Rotor Air-Gap Slot Offset for Torque Ripple Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing reluctance motors face challenges in reducing torque ripple while maintaining motor efficiency and avoiding increased complexity in the stator or rotor, which also leads to higher costs due to increased current requirements and frequency converter costs.
Innovation Solution
The design incorporates a rotor with air-gap slots that have offset end parts relative to their main body parts, distributed in multiple groups around the rotor, allowing for optimized torque ripple reduction without increasing complexity, and the use of magnetic fillers like ferrite magnets or sintered neodymium-iron-boron permanent magnets to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the end part of air-gap slots is aligned with the main body part, then the motor structure is simple, but the torque ripple cannot be effectively reduced
Solution Approach 1:
The patent applies asymmetry by offsetting the end part of the air-gap slot relative to the main body part in the radial direction. This asymmetric configuration creates a non-uniform air gap that effectively reduces torque ripple while maintaining relatively simple manufacturing processes.
2Object-generated harmful factors
If non-uniform air gaps are used to reduce torque ripple, then torque ripple is reduced, but the stator or rotor complexity increases and air gap measurement becomes difficult
Solution Approach 1:
The patent segments the air-gap slot into two distinct parts: the main body part and the end part. By offsetting only the end part in the radial direction while keeping the main body part unchanged, the design achieves non-uniform air gap benefits with localized structural modification, reducing overall complexity.
Solution Approach 2:
The patent applies local quality by modifying only the end part of the air-gap slot rather than the entire slot structure. This localized offset creates the necessary non-uniform air gap for torque ripple reduction while minimizing the overall structural complexity of the motor.
3Ease of manufacture
If induction motor or reluctance motor is used to replace rare earth permanent magnet motor, then costs are reduced, but motor efficiency decreases
Solution Approach 1:
The patent changes the geometric parameters of the air-gap slots by introducing an offset between the end part and main body part. This parameter modification optimizes the magnetic field distribution and torque characteristics, enabling efficiency improvement in induction and reluctance motors without increasing material costs.
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 ripple and decreases the costs of variable-speed motors while maintaining high efficiency, ensuring sufficient mechanical strength and magnetic path saturation.
Implementation Method 1
End parts of air-gap slots have an offset with a predetermined distance and/or a predetermined angle relative to main body parts adjacent immediately to the end parts, creating non-uniform air gap to reduce torque ripple
Implementation Method 2
The rotor may include magnetic fillers, for example, ferrite magnets or sintered neodymium-iron-boron permanent magnets
Data Source
AI summary
Embodiments describe a motor. The motor includes a stator, and a rotor, which is arranged within the stator. An end part of at least one air-gap slot of the rotor has an offset with a predetermined distance and/or a predetermined angle relative to a main body part adjacent immediately to the end part. With the offset of a predetermined distance and/or a predetermined angle configured at the end part of at least one air-gap slot of the rotor, ripple torque of the motor is effectively lower down while complexity of the motor, stator or rotor will not be increased.