Induction Rotor Assembly with Thin Foils for Skin Effect Loss Reduction
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Solution Overview
Problem
Current induction rotor assemblies in electric vehicles face high skin effect leading to undesirable resistance, limited motor power density, and reduced torque capability due to bar winding, which affects current distribution within conductor bars.
Innovation Solution
The induction rotor assembly incorporates a laminated stack with grooves containing copper or copper-graphene composite foils between conductor bars, secured by end rings, enhancing electrical conductivity and reducing resistance through improved current flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If bar winding is used to improve stator fill factor, then motor power density is improved, but skin effect increases causing higher resistance and energy loss
Solution Approach 1:
The patent applies local quality by using copper foils with specific thicknesses (15-25 micrometers) at specific locations (conductor bar surfaces) where current density is highest during startup. This localized copper reinforcement addresses the skin effect problem precisely where it occurs most severely, without requiring changes to the entire conductor bar structure.
Solution Approach 2:
The patent uses composite materials by combining copper foils with aluminum conductor bars. The copper-copper foil interface creates a composite structure that leverages copper's superior conductivity at the surface (where skin effect dominates) and aluminum's cost-effectiveness and adequate conductivity in the core regions.
2Power
If bar winding is used to improve stator fill factor, then motor power density is improved, but resistance increases during startup and normal operation
Solution Approach 1:
The patent applies local quality by using copper foils with specific thicknesses (15-25 micrometers) at specific locations (conductor bar surfaces) where current density is highest during startup. This localized copper reinforcement addresses the skin effect problem precisely where it occurs most severely, without requiring changes to the entire conductor bar structure.
Solution Approach 2:
The patent uses composite materials by combining copper foils with aluminum conductor bars. The copper-copper foil interface creates a composite structure that leverages copper's superior conductivity at the surface (where skin effect dominates) and aluminum's cost-effectiveness and adequate conductivity in the core regions.
3Reliability
If conventional copper foils are used, then electrical conductivity is improved, but torque capability and power density remain limited
Solution Approach 1:
The patent uses composite materials by combining copper foils with aluminum conductor bars. The copper-copper foil interface creates a composite structure that leverages copper's superior conductivity at the surface (where skin effect dominates) and aluminum's cost-effectiveness and adequate conductivity in the core regions.
Solution Approach 2:
The patent applies parameter changes by optimizing the copper foil thickness to a specific range (15-25 micrometers). This precise parameter control ensures sufficient conductivity improvement while maintaining mechanical integrity and avoiding excessive copper usage that would increase cost and weight.
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
The solution increases motor efficiency by minimizing resistance during startup and normal operation, improving power density and torque capability by utilizing the skin effect effectively.
Implementation Method 1
Each one of the plurality of foils is disposed between each one of the plurality of conductor bars and each one of the grooves
Implementation Method 2
When an electric current is applied to the stator, a magnetic field is created that interacts with the rotor and the conductor bars. This interaction causes the rotor to rotate, which in turn produces mechanical energy.
Implementation Method 3
the bar winding can lead to a high skin effect or a tendency of an alternating electric current to become distributed within each conductor bar such that current density is largest near the conductor bar surface while decreasing exponentially with greater depths in each conductor bar
Data Source
AI summary
An induction rotor assembly is provided. The induction rotor assembly includes a laminated stack, a plurality of foils, a plurality of conductor bars, a first end ring, and a second end ring. The laminated stack includes a body with an outer circumferential surface with a plurality of grooves extending from the first end to the second end. Each one of the plurality of foils is disposed within one of the grooves. Each of the foils is disposed between each of the conductor bars and each of the grooves. Each of the plurality of conductor bars includes a first conductor end and a second conductor end. The first end ring mates with a surface of each first conductor end. The second end ring mates with a surface of each second conductor end, and the plurality of conductor bars extends between the first end ring and the second end ring.