Rotor Outer Peripheral Shape Optimization for Cogging Torque Reduction
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Solution Overview
Problem
Conventional methods for optimizing the shape of a rotor to reduce cogging torque are insufficient in eliminating the fundamental component, often resulting in reduced motor output and increased costs due to complex skew structures.
Innovation Solution
A rotor with a specific outer peripheral shape defined by equations that optimize the distance between the rotor center and its outer periphery, using parameters α, β, γ, and μ to minimize cogging torque, eliminating the need for skew structures and maintaining a consistent phase relationship between the rotor and stator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a skew structure is adopted to eliminate the fundamental component of cogging torque, then the cogging torque is reduced, but the motor output is reduced and the device complexity increases
Solution Approach 1:
The invention changes the geometric parameters of the rotor by optimizing the outer peripheral shape according to specific equations involving parameters α, β, γ, and μ. This modifies the distance r(θ) between the rotor center and outer periphery, thereby changing the magnetic interaction characteristics to eliminate the fundamental component of cogging torque without requiring skew structures that would reduce motor output.
Solution Approach 2:
The invention introduces asymmetry in the rotor's outer peripheral shape through the optimized distance function r(θ) that varies with angle θ. This asymmetric design creates specific magnetic flux distribution patterns that cancel out the fundamental component of cogging torque, achieving torque reduction without the symmetric skew structure that would compromise motor output.
2Object-generated harmful factors
If a skew structure is adopted to eliminate the fundamental component of cogging torque, then the cogging torque is reduced, but the device complexity and manufacturing costs increase
Solution Approach 1:
The invention modifies the rotor design by changing geometric parameters defined in the distance function r(θ) with angles θ and various parameters (α, β, γ, μ). This parameter optimization approach achieves cogging torque elimination through mathematical optimization of the rotor shape, avoiding the need for complex skew structures with multiple rotor core blocks and alignment requirements.
Solution Approach 2:
The invention extracts and eliminates the fundamental component of cogging torque through specific geometric optimization of the rotor outer periphery. By removing the need for skew structures entirely, the invention simplifies the rotor design to a single integrated structure rather than multiple skewed rotor core blocks, reducing both device complexity and manufacturing complexity.
3Object-generated harmful factors
If the rotor shape is optimized to reduce cogging torque, then the fundamental component is reduced, but the remaining fundamental component cannot be completely eliminated
Solution Approach 1:
The invention uses comprehensive parameter optimization in the distance function r(θ) involving four parameters (α, β, γ, μ) to precisely control the rotor outer peripheral shape. This multi-parameter optimization enables complete elimination of the fundamental component of cogging torque by creating specific magnetic flux distribution patterns, achieving more complete elimination than conventional single-parameter shape optimizations.
Data Source
AI summary
A motor according to an embodiment of the present invention includes a rotor having a rotor core and a plurality of magnetic poles including permanent magnets provided in the rotor core; and a stator having a stator core in which a plurality of teeth disposed on the side of the outer periphery of the rotor so as to be opposed to the plurality of magnetic poles and slots for containing armature winding wound around the plurality of teeth are formed. The rotor is structured such that the distance r(θ) between the center of the rotor and the outer periphery thereof satisfies the following equations (1) and (2):∫-ϕϕf(θ)2-r(θ)2dθ≤ϕ(R2-r02)10(1)∫-ϕϕr1(θ)2-r(θ)2dθ>0(2)