Aluminum Foil-Wound Rotor Cooling for High-Speed Electric Machines
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Solution Overview
Problem
Copper windings in rotating electrical machines, particularly in high-speed salient-pole rotors, are heavy, limiting rotor speed and efficiency due to mass and electrical resistance, and inefficient in heat management.
Innovation Solution
Replace copper windings with oxidized aluminum foil and use V-shaped spacers for better heat extraction, combined with a conduit network for coolant flow, and secure electrical connections via cold pressure welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If copper windings are used in rotor, then electrical conductivity is improved, but mass increases which limits rotor speed
Solution Approach 1:
The patent changes the material parameter from copper to aluminum, which has higher electrical resistance but lower density. This parameter substitution allows achieving lower rotor mass while accepting higher resistance, which is compensated by reduced mass inertia effects at high speeds
Solution Approach 2:
The patent uses composite construction by combining aluminum windings with extensive cooling systems (cooling channels, heat sinks, thermal management structures). This composite approach compensates for aluminum's higher resistance through improved thermal management that prevents resistive heating
2Speed
If rotor mass is reduced to increase rotor speed, then rotational speed is improved, but heating increases due to electrical resistance
Solution Approach 1:
The patent introduces cooling media (liquid coolant or gas) as an intermediary between the aluminum windings and the external environment. This intermediary carries heat away from the windings, enabling high-speed operation without excessive temperature rise despite aluminum's higher electrical resistance
Solution Approach 2:
The patent employs hydraulic or pneumatic cooling systems with channels running through the rotor structure. Coolant flows through these channels to actively remove heat from the windings, enabling sustained high-speed operation without thermal overload
3Weight of moving object
If aluminum foil is used instead of copper wire, then mass is reduced and pole filling is improved, but heat extraction becomes more challenging
Solution Approach 1:
The patent transitions from point-contact wire windings to planar foil windings, adding surface area dimension. This dimensional change provides extensive surface area for heat transfer, compensating for aluminum's lower thermal conductivity compared to copper
Solution Approach 2:
The aluminum foil serves multiple functions simultaneously: it provides electrical conduction, structural support for the winding, and a large surface area for heat transfer. This multi-functionality compensates for aluminum's lower thermal conductivity by using surface area rather than material conductivity
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
Reduces rotor mass and heat generation, enhances rotational speed, and improves thermal management and electrical performance.
Implementation Method 1
said locking wedge being configured to exert pressure on said rotor winding in the direction of said pole body
Implementation Method 2
the heat exchange surface between turns is greater with foil, which has a flat surface, than with wire
Implementation Method 3
The invention also proposes a V-shaped spacer for extracting heat from the foil windings
Implementation Method 4
the rotor winding of the pole being electrically connected to an electrical power source, via electrical connections
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The invention relates to a rotating electrical machine rotor comprising: - a plurality of poles each extending along a first radial axis with respect to the rotor and along a second axis parallel to the rotor with respect to the rotor, each pole comprising a pole body, - a rotor winding per pole, positioned against the pole body, the rotor winding taking the form of a strip extending over the length of said pole body along the first radial axis wound against the pole body, - a plurality of closing wedges, a closing wedge of the plurality of closing wedges being in contact with a rotor winding associated with a pole body, said closing wedge being configured to exert pressure on said rotor winding in the direction of said pole body.