Internal E-Machine Cooling Layout for Shorter Winding Heat Paths
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Solution Overview
Problem
Current cooling systems for electric machines, such as those described in CN107919745A, face limitations in reducing thermal resistances and efficiently managing winding losses due to high temperatures within slots and long thermal paths between conductors and the casing liquid cooling jacket, which restricts the improvement of e-machine performance.
Innovation Solution
An internal cooling system for electric machines that incorporates a periphery liquid cooling jacket in contact with stator laminations and high conductivity matrices encapsulating head windings, along with slot-through liquid cooling jackets in contact with stator slot winding turns, to effectively extract conductor losses and reduce thermal resistances by minimizing the thermal path between the source and the thermal sink.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a periphery casing liquid cooling jacket is used to extract heat from stator laminations, then iron losses are cooled, but the thermal path to conductors remains long and thermal resistance remains high
Solution Approach 1:
The liquid cooling jacket is nested inside the stator core, with cooling channels positioned within the stator laminations. This allows the cooling system to be integrated within the existing stator structure, reducing the thermal path from conductors to coolant without significantly increasing external complexity.
Solution Approach 2:
The liquid cooling jacket acts as an intermediary thermal pathway between the heat-generating conductors and the external cooling system. By placing the cooling channels in direct contact with or adjacent to the stator laminations, it creates an efficient thermal bridge that reduces overall thermal resistance.
2Temperature
If cooling channels are added inside the stator core, then thermal resistance is reduced, but manufacturing complexity increases
Solution Approach 1:
The stator core is segmented into modular laminations that can be independently manufactured and then assembled. The liquid cooling jacket is integrated as part of this modular structure, allowing for standardized manufacturing processes and reducing overall manufacturing complexity despite the internal cooling channels.
3Device complexity
If the cooling jacket is placed at the periphery, then the structure is simpler, but the thermal path from conductors to coolant is too long
Solution Approach 1:
The cooling system transitions from a peripheral (external) configuration to an internal configuration within the stator core. This dimensional change places the cooling channels in direct proximity to the heat-generating conductors, dramatically reducing the thermal path length and improving heat extraction efficiency.
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 configuration enhances the e-machine's figure of merit by increasing power density and efficiency, effectively managing conductor losses and reducing thermal resistances through improved heat exchange and reduced thermal paths.
Implementation Method 1
a periphery liquid cooling jacket in contact with the stator laminations to extract stator laminations iron losses and in contact with a high conductivity matrix encapsulating the head windings to extract head winding losses
Implementation Method 2
The proposed cooling system reduces thermal resistances (e.g., by using high thermal conductivity materials) and reduces the thermal path between the source and the thermal sink
Data Source
Figure 1
Figure 2
AI summary
An internal cooling system (100) for an electric motor (1000) comprising a Drive End, DE, casing (1010) and a Non-Drive End, NDE casing (1020), a stator (1030) with stator laminations (1030a) and stator slots (1030b), head windings (1040) and stator slot winding turns (1050), the internal cooling system (100) comprising a first liquid cooling channel (Cool IN) and a second liquid cooling channel (Cool OUT), a periphery casing liquid cooling jacket (110) connected to the first liquid cooling channel (Cool IN) and to the second liquid cooling channel (Cool OUT), DE and a NDE casing liquid cooling jackets (120, 130) configured to be established inside the DE and NDE casings (1010, 1020), respectively, and connected to the first liquid cooling channel (Cool IN) and to the second liquid cooling channel (Cool OUT), respectively, and a slot-through liquid cooling jacket (140) connected to the NDE and a DE casing liquid cooling jackets (120, 130) and configured to be established through the stator slots and in contact with the head windings (1040) and the stator slot winding turns (1050) to extract winding losses.