Rotating Electrical Machine Torque Ripple Reduction
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Solution Overview
Problem
Rotating electrical machines experience torque ripples due to magnetic saturation, leading to noise issues when coupled with external elements via gear, which existing designs fail to adequately address.
Innovation Solution
A rotating electrical machine design with a stator tooth pitch of 360 degrees divided by the number of stator teeth and a rotor tooth opening ratio between 0.8 and 1.2, combined with specific ratios of stator diameter to rotor poles and rotor tooth curvature, optimizes torque supply while minimizing torque ripples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional rotor tooth geometry is used, then manufacturing is simple, but torque ripple is high causing noise
Solution Approach 1:
The rotor tooth external face is given a curved profile instead of a straight or simple arc shape. The curvature is defined by specific geometric parameters (radius R1, offset e) that optimize the magnetic flux distribution in the air gap, thereby reducing torque ripple while maintaining manufacturability through standard machining processes.
Solution Approach 2:
The invention optimizes specific geometric parameters of the rotor tooth (opening angle α, curvature radius R1, offset e) to achieve the desired torque ripple reduction. By carefully selecting these parameters within defined ranges, the patent balances magnetic performance improvement with manufacturing simplicity.
2Object-generated harmful factors
If rotor tooth opening is increased to reduce torque ripple, then magnetic performance improves, but mechanical strength decreases
Solution Approach 1:
The patent defines specific ranges for the rotor tooth opening angle α (between 10° and 30°) and the curvature radius R1 (between 5mm and 15mm) that simultaneously achieve torque ripple reduction and maintain adequate mechanical strength. These parameter optimizations ensure that the reduced tooth opening does not compromise structural integrity.
Solution Approach 2:
The curved external face of the rotor tooth, defined by radius R1 and offset e, allows for a more gradual reduction in tooth opening angle while distributing mechanical stresses more evenly across the tooth structure, thereby maintaining strength despite the geometric modifications needed for torque ripple reduction.
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 ripples effectively while maintaining a satisfactory average torque level, improving both magnetic and acoustic performance of the machine.
Implementation Method 1
The rotor comprises a body formed by a stack of sheet metal held together in a bundle by means of a suitable fastening system. The rotor has poles formed by permanent magnets housed in cavities
Implementation Method 2
The stator comprises a body with a plurality of teeth defining slots, and a winding inserted into the stator slots
Implementation Method 3
This torque variation is due to the interaction between the rotor and the stator and depends, in particular, on the machine's magnetic saturation
Data Source
Figure 1~2a
Figure 2b~2c
Figure 3~4
AI summary
The invention relates mainly to a rotating electrical machine, in particular for a motor vehicle, comprising a stator having a stator tooth pitch equal to 360 degrees divided by the number of stator teeth, - each rotor tooth (40) having an external face (42) opposite an internal periphery of said stator, - in a radial plane (Pl_R) with respect to said axis of rotation (X), a rotor tooth opening (A2) is equal to an angle between two straight lines (D1, D2) each passing through said axis of rotation (X) and an ortho-radial end of said external face (42), and - a ratio of said rotor tooth opening (A2) expressed in degrees divided by said stator tooth pitch expressed in degrees is between 0.8 and 1.2.