Rotating Electrical Machine Rotor Torque Ripple Suppression
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Solution Overview
Problem
Existing permanent magnet embedded rotating electrical machines with flat magnets in rotational symmetry face challenges in suppressing torque ripple, which causes vibration and noise due to rapid magnetic flux density changes between adjacent magnetic poles.
Innovation Solution
The design incorporates a rotor with alternately arranged first and second flat permanent magnets, featuring concave and convex portions that bisect the angular width between magnetic poles, along with a stator with wave-wound coils, to manage magnetic flux and reduce torque ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat permanent magnets are arranged in rotational symmetry in the rotor, then the machine structure is simplified and manufacturing is easier, but torque ripple increases causing vibration and noise
Solution Approach 1:
The invention introduces auxiliary magnetic poles with different magnetic properties at specific locations between the permanent magnets. These auxiliary poles have tailored magnetic flux densities and polarities that locally modify the magnetic field distribution, thereby suppressing torque ripple without changing the overall rotational symmetry of the rotor structure
Solution Approach 2:
While maintaining the rotational symmetry of the permanent magnets, the invention introduces asymmetric auxiliary magnetic poles at specific positions between them. This localized asymmetry in magnetic pole configuration creates compensating magnetic fields that reduce torque ripple while preserving the overall symmetric rotor structure
2Object-generated harmful factors
If the number of auxiliary magnetic poles is increased, then torque ripple suppression improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The invention uses a minimal number of auxiliary magnetic poles (one or two per interval between permanent magnets) rather than increasing the total pole count significantly. This partial action approach provides sufficient torque ripple suppression while avoiding excessive device complexity and manufacturing difficulty
3Manufacturing precision
If the electrical degree range of concave portions is adjusted, then torque ripple suppression optimizes for V-shaped magnets, but the solution cannot be applied to block-form flat magnets with rotational symmetry
Solution Approach 1:
The invention determines specific electrical degree ranges (first and second electrical degrees) for the auxiliary magnetic poles based on the stator's slot configuration. These parameter specifications allow the same auxiliary pole concept to be effectively applied to block-form flat magnets with rotational symmetry, unlike previous solutions optimized only for V-shaped magnets
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 effectively suppresses torque ripple, reducing vibration and noise by optimizing the magnetic flux distribution and electrical degree settings, resulting in a smoother torque waveform and improved machine performance.
Implementation Method 1
a plurality of flat permanent magnets 17A and 17B are embedded in the rotor core 16... a stator 11 having coils 13... rotor 15 rotatably located inside the stator 11
Implementation Method 2
Rapid change in magnetic flux density occurs between the two adjacent permanent magnets... concave and convex portions that bisect the angular width between magnetic poles
Data Source
Figure 1
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Figure 3
AI summary
The permanent magnet embedded rotating electrical machine includes a rotor and a plurality of flat permanent magnets. The rotor has on an outer periphery thereof a plurality of pairs of concave portions and a plurality of convex portions. Each of the convex portions is located between the pair of concave portions. The concave portions are formed at radially outward of respective adjacent magnetic pole ends of the permanent magnet. A bridge is provided in the rotor at an angular position about an axis of the rotor between opposed magnetic pole ends of two adjacent permanent magnets. Each concave portion at radially outward of the magnetic pole end of the permanent magnet is located close to the center of the same permanent magnet in relation to the bridge next to the permanent magnet in the circumferential direction of the rotor.