Metal Oxide Insulation for Electric Machine Thermal Management
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Solution Overview
Problem
Electric motors face challenges in achieving a balance between efficiency, power-to-weight ratio, and service life due to heat dissipation issues, particularly at high voltage and frequency, where stranded conductors with insulation are used to mitigate losses but require efficient cooling and insulation for compact and lightweight designs.
Innovation Solution
The use of metal oxide insulation, such as aluminum oxide or silver oxide, on the surface of electrical conductors provides high dielectric strength and thermal conductivity, enabling efficient cooling and compact, lightweight electric machines with reduced susceptibility to vibrations and mechanical shocks, allowing for a compact and efficient design of electric machines and hybrid-electric aircraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a low motor weight is used to improve power to weight ratio, then the power to weight ratio is improved, but the efficiency deteriorates due to insufficient cooling system dimensioning
Solution Approach 1:
The patent changes the material parameter of the insulation from organic materials to metal oxide (such as aluminum oxide), which fundamentally alters the thermal conductivity parameter. This enables the insulation layer to actively participate in heat dissipation rather than merely providing electrical isolation, thus maintaining efficiency while reducing overall motor weight and cooling system requirements.
Solution Approach 2:
The metal oxide insulation layer performs multiple functions simultaneously: it provides electrical insulation (dielectric strength), thermal conduction for heat dissipation, and mechanical protection. This multi-functionality eliminates the need for separate heavy cooling systems and insulation layers, resolving the contradiction between weight reduction and efficiency maintenance.
2Duration of action of stationary object
If a correspondingly dimensioned cooling system is used to ensure long service life, then the service life is improved, but the heat dissipation deteriorates due to compact construction requirements
Solution Approach 1:
The patent fundamentally changes the thermal conductivity parameter of the insulation material from low (organic materials) to high (metal oxide with thermal conductivity of 30-40 W/mK). This parameter change enables effective heat dissipation even in compact constructions with limited cooling system dimensioning, thus maintaining service life without requiring large cooling systems.
Solution Approach 2:
The patent uses composite material structure where metal oxide insulation is applied on the surface of electrical conductors. This composite approach combines the electrical insulation properties with high thermal conductivity, enabling both long service life through adequate heat dissipation and compact construction without sacrificing either service life or heat dissipation capability.
3Loss of energy
If stranded conductors with insulation are used to mitigate losses at high frequency, then the electrical losses are reduced, but the device complexity increases due to requirements for efficient cooling and insulation
Solution Approach 1:
The metal oxide insulation layer serves multiple purposes: electrical insulation, thermal conduction, and mechanical protection. This multi-functionality reduces the overall device complexity by eliminating the need for separate heavy cooling systems and complex insulation structures, while still mitigating electrical losses through the use of stranded conductors.
Solution Approach 2:
The patent changes the thermal conductivity parameter of the insulation material, which fundamentally alters the heat dissipation mechanism. This parameter change simplifies the cooling system requirements while maintaining effective heat dissipation, thus reducing device complexity while still enabling the use of stranded conductors for loss mitigation.
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 solution allows for improved electrical insulation and thermal management, enhancing the efficiency and reliability of electric machines by maintaining high dielectric strength and facilitating efficient cooling, thus addressing the heat dissipation and compactness challenges while reducing the risk of short circuits and mechanical damage.
Implementation Method 1
a comparatively thin layer of metal oxide already advantageously has a high dielectric strength that is in the range of more than a thousand volts at a thickness of at least 10 micrometers
Implementation Method 2
Oxidized metal (e.g., aluminum oxide) advantageously exhibits good thermal conductivity, so that, in addition to adequate electrical insulation, efficient cooling due to the good thermal conductivity via the metal oxide is simultaneously possible
Implementation Method 3
the at least one conductor is oxidized on the surface
Data Source
AI summary
The electric machine comprises at least one winding (30) having at least one conductor (20) and electrical insulation for insulating one or more of the windings (30) and/or conductors (20), wherein the insulation is formed by a metal oxide. The method for producing such an electric machine having at least one winding (30) having at least one conductor (20) comprises the steps of metallizing the at least one winding (30) and/or conductor (20) with metal and oxidizing the metal. The aircraft is in particular an electric or hybrid-electric aircraft and has such an electric machine (10).