V-Shaped Magnet Rotor Core Structure for Torque Ripple Reduction
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Solution Overview
Problem
Existing rotor configurations of rotating electric machines face challenges in simultaneously increasing maximum torque and reducing stress while minimizing torque ripple.
Innovation Solution
A rotor design featuring a pair of V-shaped magnets and a rotor core with magnet holes, including a magnetic gap and a protrusion that faces the magnet's main surface, which partially widens the magnetic flux passage and controls magnetic flux density to enhance torque and reduce stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotor core has a conventional structure without protrusion, then the structure is simple, but the maximum torque cannot be increased while stress is reduced
Solution Approach 1:
The invention applies local quality by creating a protrusion at a specific location (between the first and second outermost diameter portions) of the rotor core. This localized structural modification changes the magnetic flux distribution only in the critical region, allowing increased maximum torque while reducing stress concentration at that specific location without requiring global structural changes.
Solution Approach 2:
The invention introduces a new dimensional feature (the protrusion extending radially outward) to the rotor core structure. This adds a radial dimension to the magnetic flux path control, enabling independent optimization of torque generation and stress distribution by controlling flux density in the magnetic gap through the protrusion's geometry.
2Power
If the rotor core has a conventional structure without protrusion, then the manufacturing is simple, but the torque ripple cannot be reduced
Solution Approach 1:
The protrusion creates local quality variation in the magnetic gap, producing different magnetic flux densities at different circumferential positions. This local modification smooths out the fluctuations in magnetic flux throughout the rotation cycle, thereby reducing torque ripple without requiring complex global structural changes.
3Power
If the protrusion is added to the rotor core, then the magnetic flux passage is widened and torque is increased, but the device complexity increases
Solution Approach 1:
The invention changes the geometric parameter of the rotor core by adding a protrusion with specific dimensions (extending between the first and second outermost diameter portions). This parameter change directly increases the magnetic flux passage area in the critical region, thereby increasing maximum torque while keeping the structural change relatively simple and localized.
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 increased maximum torque and reduced torque ripple, while also minimizing stress and enhancing magnet fixation, resulting in improved performance and reduced harmonic torque variations.
Implementation Method 1
a magnetic gap between the rotor core and an outermost diameter corner located on an outermost side in the radial direction among corners of the magnet, and has a protrusion formed so as to protrude toward the magnet between a first outermost diameter portion closer to a magnetic pole center of the rotor than the outermost diameter corner in an outer diameter of the magnetic gap and a second outermost diameter portion closer to a magnetic pole boundary of the rotor than the outermost diameter corner in an outermost diameter of the magnetic gap
Data Source
AI summary
A rotor of a rotating electric machine includes a pair of magnets arranged in a V shape and a rotor core provided with magnet holes into which the magnets are inserted. The rotor core has, on an outside in a radial direction, a magnetic gap between the rotor core and an outermost diameter corner located on an outermost side in the radial direction among corners of the magnet, and has a protrusion formed so as to protrude toward the magnet between a first outermost diameter portion closer to a magnetic pole center of the rotor than the outermost diameter corner in an outer diameter of the magnetic gap and a second outermost diameter portion closer to a magnetic pole boundary of the rotor than the outermost diameter corner in an outermost diameter of the magnetic gap, and the protrusion faces a main surface of the magnet.