Ceramic Cooling Inserts for Electric Machine Winding Heat Dissipation
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Solution Overview
Problem
Conventional cooling methods for electric machine windings, such as using high thermal conductivity laminations and radial projections, suffer from inefficient heat transfer and increased electromagnetic losses due to flux leakage and high thermal resistance from electrical insulation, which reduces torque production efficiency.
Innovation Solution
Incorporating high thermal conductivity, low electrical conductivity ceramic inserts, such as aluminium nitride, between electromagnetic windings to facilitate heat transfer and dissipation through a cooling fluid flow, eliminating the need for separate electrical insulation and reducing thermal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high thermal conductivity laminations are introduced into the stator core, then heat transfer from windings is improved, but the overall thermal conductivity deteriorates because these laminations form a minority of the core laminations
Solution Approach 1:
A slot liner made of electrically insulating material is introduced as an intermediary between the windings and the cooling inserts. This slot liner enables electrical insulation while maintaining thermal contact, allowing heat to transfer effectively from the windings to the cooling inserts without electrical short circuits.
2Strength
If radial projections are provided from the stator core into the gaps between windings, then structural support and contact area are increased, but flux leakage paths are created reducing electromagnetic efficiency
Solution Approach 1:
Cooling inserts made of electrically insulating material with high thermal conductivity are introduced as intermediaries between the stator core and the windings. These inserts provide the necessary mechanical support and thermal contact while blocking flux leakage paths, as the insulating material prevents magnetic flux from taking short circuits through the projections.
3Reliability
If electrically insulating slot liner is provided between windings and stator core, then electrical insulation is ensured, but thermal resistance increases significantly reducing cooling efficiency
Solution Approach 1:
The slot liner is made of a composite material or material with specific properties: electrically insulating but thermally conductive. This composite material simultaneously provides electrical insulation to prevent short circuits and thermal conductivity to maintain efficient heat transfer from the windings to the cooling inserts.
Solution Approach 2:
The thermal and electrical properties of the slot liner material are optimized by selecting materials with high thermal conductivity and high electrical resistivity. This parameter change allows the slot liner to perform both electrical insulation and thermal conduction functions effectively, reducing thermal resistance while maintaining electrical isolation.
4Temperature
If conventional cooling methods are used, then cooling is provided, but thermal resistance dominates the thermal performance particularly at higher temperatures where winding losses are greater
Solution Approach 1:
Cooling inserts are introduced as intermediaries that provide a direct thermal pathway from the windings to the cooling fluid channels. These inserts maintain intimate thermal contact with the windings through the slot liner interface, enabling efficient heat transfer even at high temperatures where winding losses are proportionally greater.
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 ceramic inserts enhance heat transfer efficiency by six times compared to traditional methods, reducing thermal resistance by approximately 40% and minimizing flux leakage, thereby improving torque production and cooling performance.
Implementation Method 1
the cooling insert comprises a high thermal conductivity, low electrical conductivity material... in use a cooling fluid being arranged to flow through the at least one cooling inserts to facilitate heat transfer and dissipation from the electromagnetic windings
Data Source
AI summary
A component of an electric machine 46, the component comprising a core 10; two or more teeth 14 extending radially therefrom; at least one electromagnetic winding 12, each winding 12 around at least one of the teeth 14; wherein the core 10 having a cooling arrangement including at least one cooling insert 48 located between adjacent windings 12 and whereby in use a cooling fluid being arranged to flow through the at least one cooling insert 48 to facilitate heat transfer and dissipation from the electromagnetic windings 12. The cooling inserts providing improved cooling, structural support to the windings, and electrical insulation between the windings and the core.