Split Core Stator Design for PMSM Torque Density
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Solution Overview
Problem
Existing permanent magnet synchronous machines face issues with reduced torque density due to magnetic flux short-circuiting and difficulty in winding high-density armature windings, which can lead to cracking and chipping of magnets between split teeth during tight winding.
Innovation Solution
A stator design featuring split core blocks with permanent magnets sandwiched between teeth that are connected via thin bridges, reducing the force applied to the magnets during winding and minimizing leakage magnetic flux, thereby preventing cracking and chipping, and using a method of manufacturing where magnetic steel plates are stacked and formed with caulked portions to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the permanent magnet is embedded in the center portion of the stator tooth, then the structure is simple and robust, but the magnetic flux is short-circuited on the rotor opposite-side, resulting in reduction in torque density
Solution Approach 1:
The stator tooth is divided into two separate teeth by splitting it perpendicular to the magnetic flux direction. The permanent magnet is embedded between these two split teeth rather than in the center of a single tooth. This segmentation prevents magnetic flux short-circuiting while maintaining structural simplicity, thereby resolving the contradiction between structural simplicity and torque density.
2Productivity
If the magnet is embedded between the split teeth, then the winding can be wound at high space factor, but tension must be applied to the winding which may crack and chip the magnet
Solution Approach 1:
Connection teeth are provided on the axial end portions of the pair of teeth sandwiching the permanent magnet before the winding process. These connection teeth connect the pair of teeth together in advance, creating a reinforced structure that prevents magnet cracking and chipping during the subsequent winding operation. This preliminary structural preparation allows high-density winding while maintaining magnet integrity.
3Loss of substance
If the core sandwiching the magnet has portions entirely held in contact with the magnet in the axial direction, then powder drop is prevented, but the structure becomes more complex
Solution Approach 1:
The core sandwiching the magnet is divided into multiple separate teeth rather than forming a continuous structure. These segmented teeth are arranged such that their end portions are held in contact with the permanent magnet in the axial direction, preventing magnet powder drop. The segmentation approach achieves powder retention while maintaining manufacturing simplicity through standardized tooth components.
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 design achieves a high torque density with reduced leakage magnetic flux and prevents magnet cracking/chipping by distributing the winding force effectively, while also reducing material costs and manufacturing complexity.
Implementation Method 1
a permanent magnet; a pair of teeth arranged on both ends of the permanent magnet so as to sandwich the permanent magnet in the rotation direction
Data Source
AI summary
A permanent magnet synchronous machine includes a stator including a plurality of split core blocks that are continuously arranged in a rotation direction of a rotor. The plurality of split core blocks each includes: a permanent magnet; a pair of teeth arranged on both ends of the permanent magnet so as to sandwich the permanent magnet in the rotation direction; and connection teeth, which are provided on axial end portions of the pair of teeth sandwiching the permanent magnet, and are configured to connect the pair of teeth.