Liquid Cooled Stator Teeth with Integrated Channels
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Solution Overview
Problem
Existing electric machine stators face significant thermal resistance issues due to the combination of thermal resistance elements, limiting their performance, especially in high specific power applications where efficient heat rejection is crucial.
Innovation Solution
The design incorporates a stator core with a plurality of layers featuring apertures that form fluid channels within the teeth and back iron portions, allowing for direct coolant flow through the stator core, reducing thermal resistance by minimizing heat transfer path lengths and maintaining low coolant head losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a liquid cooled enclosure with slot liners and electrical varnish is used to cool the stator, then the stator can be cooled, but the thermal resistance increases due to multiple heat transfer barriers
Solution Approach 1:
The invention extracts and eliminates the thermal resistance elements (slot liners and electrical varnish) from the heat transfer path. By removing these insulating layers that were previously necessary for electrical isolation, the patent creates a direct thermal pathway from the winding to the coolant, dramatically reducing thermal resistance while maintaining cooling effectiveness.
Solution Approach 2:
The patent introduces a new intermediary structure - a cooling plate with integrated coolant channels that provides both electrical isolation and thermal conduction. This cooling plate acts as a mediator that replaces the thermally resistive slot liners and varnish, allowing efficient heat transfer from the winding to the coolant while maintaining necessary electrical insulation.
2Power
If high specific power is achieved by increasing shaft speed and torque, then power output increases, but heat generation increases rapidly limiting performance
Solution Approach 1:
The invention implements continuous coolant flow through the stator core via integrated cooling channels, ensuring uninterrupted heat removal. The coolant systematically traverses through the back iron and teeth, maintaining continuous thermal management that enables sustained high power operation without thermal buildup limiting performance.
Solution Approach 2:
The patent utilizes hydraulic cooling with coolant flowing through precisely engineered channels within the stator core. This hydraulic system efficiently transports heat away from the winding and core, using fluid dynamics to maintain thermal management during high specific power operation where heat generation is rapid and intense.
3Loss of energy
If coolant channels are integrated within the stator core teeth and back iron, then thermal resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The invention merges the cooling function directly into the stator core structure by integrating coolant channels within the back iron and teeth. This consolidation eliminates separate cooling components and their associated thermal interfaces, reducing overall thermal resistance while the modular design approach keeps manufacturing manageable.
Solution Approach 2:
The patent modifies the structural parameters of the stator core by incorporating cooling channels during the manufacturing process. By changing the geometric parameters of the back iron and teeth to include integrated channels, the design achieves low thermal resistance without requiring complex post-assembly cooling systems.
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 approach significantly reduces the overall winding to coolant thermal resistance, enabling a substantial increase in continuous specific power by enhancing heat transfer efficiency and maintaining low thermal resistance within the stator.
Implementation Method 1
Heat produced within the winding may be constrained to flow through a series of elements... before reaching coolant which flows within the enclosure
Implementation Method 2
Heat is received by the core teeth and flows radially through the back iron and on to the enclosure
Data Source
AI summary
A system for cooling the teeth of an electric machine stator. The stator includes a stator core that may be formed of a plurality of laminations. Each lamination has a plurality of back iron apertures, a plurality of tooth tip apertures, and a plurality of elongated apertures. When the laminations are assembled to form the stator core, the back iron apertures align to form back iron inlet channels and back iron outlet channels, and the tooth tip apertures align to form tooth tip cooling channels. The elongated apertures are L-shaped and connect the back iron inlet channels and back iron outlet channels to the tooth tip channels. Cooling fluid may flow, for example, axially through a back iron inlet channel, azimuthally and radially inward through an elongated aperture to a tooth tip, axially along a tooth tip channel, and to a back iron outlet channel through another elongated aperture.