Segmented Rotor Core Design for Torque Ripple Reduction
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Solution Overview
Problem
Related rotating electric machines with segmented rotor cores experience increased torque ripple due to harmonic components of magnetomotive force interacting with rotating magnetic fields, which degrades ride comfort in elevator hoisting machines.
Innovation Solution
A rotating electric machine design with an annular rotor core divided into segments, where the number of segments differs from the greatest common divisor or its multiples of the rotor poles and stator slots, reducing torque ripple by mismatching the phase of harmonic components with rotating magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the rotor core is divided into segment cores to improve material yield, then the material yield is improved, but torque ripple increases due to harmonic components
Solution Approach 1:
The rotor core is divided into a plurality of segment cores arranged in the circumferential direction, which improves material yield by reducing waste from annular punching. However, this segmentation introduces harmonic components that increase torque ripple.
Solution Approach 2:
The patent changes the parameter of segment core configuration by introducing yoke cores between adjacent segment cores. This modification alters the magnetic path and suppresses the harmonic components generated by segmentation, thereby reducing torque ripple while maintaining the material yield benefits of segmentation.
2Volume of moving object
If the number of segments is increased to achieve downsizing in axial dimension, then the radial dimension can be reduced, but torque ripple becomes more liable to be generated
Solution Approach 1:
The rotor core is segmented into multiple segment cores arranged circumferentially, enabling compact axial dimension. The segmentation allows for a thinner rotor structure while maintaining structural integrity through the distributed segment configuration.
Solution Approach 2:
Yoke cores are introduced as intermediary elements between adjacent segment cores. These yoke cores serve as magnetic flux pathways that connect the segment cores and suppress the generation of harmonic components, thereby reducing torque ripple even when the number of segments is increased for downsizing.
3Loss of substance
If segment cores are arranged in circumferential direction to improve material yield, then material utilization is improved, but harmonic components of magnetomotive force are generated
Solution Approach 1:
The rotor core is divided into multiple segment cores that are arranged in the circumferential direction. This segmentation improves material yield by allowing more efficient use of steel sheets during manufacturing, reducing waste from annular punching operations.
Solution Approach 2:
Yoke cores are positioned between adjacent segment cores to act as magnetic flux intermediaries. These yoke cores provide continuous magnetic pathways that smooth out the magnetomotive force distribution, thereby suppressing harmonic components generated by the segmented 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
The design effectively suppresses torque ripple, enhancing ride comfort in elevator hoisting machines by ensuring the number of segments does not align with the divisor or multiple of the greatest common divisor of rotor poles and stator slots, thereby reducing harmonic interference.
Implementation Method 1
a rotor including: an annular rotor core which is arranged coaxially with the stator through a magnetic gap and is rotatable; and a plurality of magnetic poles arranged on the rotor core in the circumferential direction
Implementation Method 2
a magnetic gap defined between a stator and a rotor
Data Source
AI summary
Provided is a rotating electric machine, including: a stator including: an annular core back; and a plurality of teeth projecting in a radial direction from the core back and being arranged in a circumferential direction, the plurality of teeth having slots each formed between the plurality of teeth adjacent to each other in the circumferential direction; and a rotor including: an annular rotor core which is arranged coaxially with the stator through a magnetic gap; and a plurality of magnetic poles arranged on the rotor core in the circumferential direction, wherein the rotor core includes a plurality of segment cores formed by dividing the rotor core in the circumferential direction with at division surfaces, and wherein the number of segments of the rotor core is different from a divisor and a multiple of the greatest common divisor of the number of poles of the rotor and the number of slots.