Asymmetric Spoke Rotor Pole Groups for Torque Ripple Reduction
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Solution Overview
Problem
Electrical machines often experience high cogging torque and torque ripple due to their design, which existing technologies have not effectively mitigated without generating lateral forces.
Innovation Solution
The rotor design features multiple identical pole groups with at least two poles each, where the poles differ in pitch and geometry, preventing simultaneous and uniform contact with stator teeth, thereby reducing cogging torque and torque ripple, and incorporating a ferromagnetic support with permanent magnets arranged in a spoke-like fashion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional rotor designs with uniform poles are used, then the rotor structure is simple and uniform, but high cogging torque and torque ripple are generated
Solution Approach 1:
The patent applies asymmetry by making at least two poles in each pole group have different geometries (different pole arc lengths or different shapes). This asymmetric design within the pole group prevents all poles from engaging stator teeth simultaneously and uniformly, thereby reducing cogging torque and torque ripple while maintaining a uniform rotor structure through repetition of identical pole groups
Solution Approach 2:
The rotor is segmented into multiple identical pole groups, where each pole group contains at least two poles. This segmentation allows the rotor to have both uniformity (through repetition of identical pole groups) and asymmetry (within each pole group), resolving the contradiction between structural uniformity and cogging torque reduction
2Object-generated harmful factors
If fractional-slot windings are used in the stator, then cogging torque is reduced, but the device complexity increases and compatibility with full-hole windings is lost
Solution Approach 1:
The patent extracts the cogging torque reduction function from the stator winding configuration and transfers it to the rotor pole geometry. By making poles within each group asymmetric while keeping the pole groups identical and repeating them, the rotor alone can reduce cogging torque without requiring complex fractional-slot windings in the stator
Solution Approach 2:
The patent changes the geometric parameters of the poles (pole arc length, pole shape) within each pole group to create asymmetry. This parameter change allows the rotor to reduce cogging torque independently of the stator winding configuration, enabling compatibility with simple full-hole windings
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 effectively reduces cogging torque and torque ripple while avoiding lateral forces, ensuring a uniform rotor structure and efficient operation as both a motor and generator.
Implementation Method 1
A plurality of magnets are located within the carrier. These magnets are, in particular, permanent magnets
Implementation Method 2
The electric machine can be operated as an electric motor or generator
Implementation Method 3
The rotor comprises a ferromagnetic carrier
Data Source
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AI summary
The present invention relates to a rotor (3) of an electric machine (1) comprising a ferromagnetic support (4) and a plurality of magnets (5) arranged in a spoke-like manner around the axis of rotation (30) of the rotor (3), such that the magnetic poles (N, S) of the magnets (5) are aligned in the circumferential direction (31) and magnetic poles (N, S) facing each other are oriented in the same direction, wherein each pair of opposing magnetic poles (N, S) and the intermediate portion of the support (4) form a pole (6) of the rotor (3), wherein at least two poles (6) form a pole group (10), wherein the pole group (10) is completely repeated in the circumferential direction (31), and wherein at least two poles (6) in the pole group (10) are different from each other.