Electric Machine Rotor Truss Structure for Weight Reduction
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Solution Overview
Problem
Existing electric machine rotors in electrified vehicles face challenges in achieving higher power outputs and improved thermal management due to weight and stiffness limitations, which affect the extended drive range and performance of these vehicles.
Innovation Solution
The rotor design incorporates a truss structure with triangle-shaped holes tessellated about central regions, forming a starburst pattern, which reduces strain energy and enhances structural stiffness while maintaining magnetic flux paths, resulting in a lighter and more durable rotor with increased power output capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rotor uses a solid structure to maintain stiffness and strength, then structural integrity is improved, but weight increases and power output capability deteriorates
Solution Approach 1:
The rotor structure is segmented into a truss framework with triangular openings, dividing the solid rotor into a lattice structure. This segmentation maintains structural integrity through the triangular geometry while removing unnecessary material to reduce weight by 20%.
Solution Approach 2:
The rotor employs a composite structure combining magnetic material segments with a truss framework. This composite approach allows the magnetic portions to maintain electromagnetic functionality while the truss structure provides mechanical support with reduced weight.
2Power
If the rotor weight is reduced to increase power output, then power output capability is improved, but structural stiffness deteriorates
Solution Approach 1:
The rotor is segmented into a truss structure that strategically positions material where it provides maximum structural efficiency. The triangular openings are arranged to maintain stiffness while minimizing weight, enabling power output improvement without compromising structural stability.
Solution Approach 2:
The rotor applies local quality by concentrating magnetic material in specific regions where it is needed for electromagnetic function, while using the truss structure in other regions for mechanical support. This localized material distribution optimizes both power output and structural stiffness.
3Weight of moving object
If the rotor uses a truss structure with triangle-shaped holes to reduce weight, then weight is reduced and power output is improved, but magnetic flux paths may be disrupted
Solution Approach 1:
The truss structure is designed with local quality variations where magnetic material is concentrated along the flux paths to maintain magnetic reliability, while triangular openings are positioned in regions where they do not interfere with magnetic flux. This ensures weight reduction without disrupting magnetic flux paths.
Solution Approach 2:
The triangular openings are arranged in a pattern that considers three-dimensional magnetic flux paths, ensuring that the two-dimensional holes do not intersect with the three-dimensional flux trajectories. This dimensional consideration maintains magnetic flux integrity while achieving weight reduction.
Data Source
AI summary
An electric machine assembly for a vehicle is provided. The electric machine is in operational communication with a traction battery and includes a stator core defining a cavity and a rotor disposed within the cavity having an inner region defined by sets of triangle-shaped holes tessellated about respective central regions to form a truss structure such that the holes of the truss structure, during operational rotation, do not influence magnetic flux paths generated by magnets of the rotor. The rotor may have a strain energy value less than or equal to 16,100 Joules. The truss structure may include pairs of symmetrical portions each including segments arranged with adjacent rotor portions to define the triangle-shaped holes.