Aircraft Motor Two-Phase Cooling for Higher Power Density
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Solution Overview
Problem
Traditional electric motors for aircraft applications are limited by thermal management systems that add weight and volume, restricting power density due to heat dissipation limitations from motor windings, and require advanced cooling technologies to mitigate thermal limitations.
Innovation Solution
Aircraft electric motors with integrated cooling systems utilizing a two-phase cooling scheme, including a separator to separate liquid and vapor phases of a refrigerant, directing the liquid phase to critical components for enhanced cooling efficiency and a closed-loop system with a mixer and heat exchanger to manage fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling methods (natural convection or liquid cooling) are used, then heat dissipation is achieved, but weight and volume increase due to the addition of cooling jackets
Solution Approach 1:
The cooling channels are integrated directly into the stator structure, merging the cooling system with the motor body. This eliminates the need for separate cooling jackets, thereby reducing weight and volume while maintaining effective heat dissipation from the windings
Solution Approach 2:
The patent uses a two-phase refrigerant system with liquid and vapor phases to cool the motor. The liquid refrigerant flows through channels in the stator to absorb heat, then evaporates to remove thermal energy, providing efficient cooling without requiring heavy conventional cooling machinery
2Temperature
If conventional cooling methods are used, then heat dissipation is achieved, but volume increases due to the addition of cooling jackets
Solution Approach 1:
The cooling channels are integrated directly into the stator structure, merging the cooling system with the motor body. This eliminates the need for separate cooling jackets, thereby reducing weight and volume while maintaining effective heat dissipation from the windings
Solution Approach 2:
The cooling channels are nested within the stator structure itself, with the refrigerant flow path embedded in the motor's internal geometry. This nested arrangement allows the cooling system to occupy no additional external volume beyond the motor's existing footprint
3Power
If internal thermal resistance is reduced to increase allowable electrical current, then power density increases, but heat generation in windings increases
Solution Approach 1:
The patent employs phase change of the refrigerant (liquid to vapor) within the cooling channels to absorb large amounts of heat from the windings. This phase transition mechanism enables the system to handle high heat generation from increased electrical current while maintaining safe operating temperatures
Solution Approach 2:
The two-phase refrigerant system efficiently removes heat generated by high electrical currents through controlled evaporation in the cooling channels, enabling higher power density operation without excessive temperature rise in the windings
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
Improves thermal management by ensuring critical components receive adequate liquid coolant, enhancing power density and reducing weight, while maintaining efficient operation under high loads.
Implementation Method 1
a liquid cooling path configured to direct flow of the working fluid through, at least, the cooling channels of the motor unit
Implementation Method 2
Conventional motor thermal management includes natural convection from large fins on the outside of a motor jacket
Implementation Method 3
a separator arranged upstream of each of the liquid cooling path and the vapor cooling path and configured to direct a liquid portion of the working fluid into the liquid cooling path and configured to direct a vapor portion of the working fluid into the vapor cooling path
Implementation Method 4
a vapor cooling path configured to direct flow of the working fluid through the drive unit
Implementation Method 5
a heat exchanger arranged along the cooling fluid flow path and configured to cool the working fluid to a liquid state
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
Aircraft electric motors include a motor unit (404) having a rotor and a stator. The stator includes a plurality of windings and cooling channels arranged to provide cooling thereto. A drive unit (406) is configured to drive operation of the motor unit. A cooling system includes a working fluid arranged within a cooling fluid flow path, wherein the cooling fluid flow path includes a liquid cooling path (412) configured to direct flow of the working fluid through, at least, the cooling channels of the motor unit and a vapor cooling path (414) configured to direct flow of the working fluid through the drive unit (406) and a separator (410) arranged upstream of each of the liquid cooling path (412) and the vapor cooling path (414) and configured to direct a liquid portion of the working fluid into the liquid cooling path (412) and configured to direct a vapor portion of the working fluid into the vapor cooling path (414).