Skewed Switched Reluctance Motor Teeth for Lower Torque Ripple
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Solution Overview
Problem
Conventional switched reluctance motors face challenges in reducing torque ripple and improving efficiency due to the presence of low reluctance paths between adjacent stator poles, which limits their performance, especially at high speeds and low speeds.
Innovation Solution
The design incorporates a stator with teeth arranged in phase groups, where each phase group includes two teeth mechanically joined through a magnetically permeable bridge, with a circumferential skewing angle that varies between 0.01 to 0.25 times the pitch angle, and a rotor with evenly spaced teeth, allowing for relative movement and reducing phase resistance and torque ripple by optimizing tooth geometry and skewing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional stator poles are used with even spacing, then manufacturing is simple, but torque ripple is high and efficiency is limited
Solution Approach 1:
The patent applies asymmetry by skewing the stator teeth circumferentially by an angle between 0.01 to 0.25 times the pitch angle. This asymmetric positioning of teeth relative to the rotor teeth eliminates low reluctance paths between adjacent stator poles, thereby reducing torque ripple and improving motor efficiency without significantly complicating manufacturing
Solution Approach 2:
The patent implements local quality by providing different tooth geometries for different stator teeth within the same phase group. Specifically, one tooth has a first geometry while the other tooth has a second geometry, allowing optimization of magnetic flux distribution and reluctance characteristics in different local regions to reduce torque ripple
2Productivity
If stator teeth are skewed to reduce torque ripple, then torque ripple decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by optimizing the skewing angle to be within a specific range (0.01 to 0.25 times the pitch angle). This controlled parameter change achieves effective torque ripple reduction while keeping the skewing angle small enough to maintain reasonable manufacturing precision requirements. The geometric parameters of teeth are also optimized to balance performance and manufacturability
3Loss of energy
If low reluctance paths are eliminated through tooth geometry optimization, then efficiency improves, but device complexity increases
Solution Approach 1:
The patent uses asymmetry in tooth geometry design where teeth in the same phase group have different geometries. This asymmetric design effectively eliminates low reluctance paths between adjacent stator poles, reducing energy losses. The complexity is managed by maintaining the basic stator structure while optimizing specific tooth geometries
Solution Approach 2:
The patent applies local quality by providing different tooth geometries at different locations. Each tooth geometry is optimized for its specific position to prevent low reluctance paths, while the overall stator construction remains relatively simple. This localized optimization reduces energy losses without requiring complete redesign of the entire stator
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 configuration reduces torque ripple, improves efficiency, and increases flexibility in motor design, particularly at high-speed operations, while allowing for reduced motor weight and increased power density.
Implementation Method 1
each phase group including two adjacent teeth mechanically joined together through a magnetically permeable bridge
Implementation Method 2
the separation angle equal to the pitch angle plus a circumferential skewing angle or the pitch angle minus the circumferential skewing angle
Data Source
AI summary
A switched reluctance motor. The motor includes a first member having a plurality of teeth arranged in a plurality of phase groups, each phase group including two teeth mechanically joined together through a magnetically permeable bridge. The motor also includes a second member mounted adjacent the first member allowing relative movement between the first and second members, the second member having a plurality of teeth evenly spaced from one another by a pitch in a direction of relative movement between the first and second members. Each phase group includes a first tooth and a second tooth which is separated from the first tooth by a phase group tooth spacing in the direction of relative movement between the first and second members, the phase group tooth spacing equal to a whole multiple of the pitch plus a skewing factor or a whole multiple of the pitch minus the skewing factor.