Stator Tube Cooling Layout for Rotor-Isolated Electric Machines
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Solution Overview
Problem
High energy density electric machines, such as brushless AC/DC machines, face challenges in effectively removing heat generated within the stator and rotor, with existing cooling systems often increasing system weight and complexity due to multiple fluid loops and types.
Innovation Solution
A cooling system that utilizes a common liquid circuit integrating the electric machine with the prime mover, where a pump circulates a cooling fluid through the stator to remove heat via conduction and supplies it to bearings for lubrication, while preventing fluid contact with the rotor, thereby reducing heat generation in the rotor and simplifying the cooling system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If a common liquid cooling circuit is used for both the prime mover and electric machine, then system weight and complexity are reduced, but heat removal effectiveness from the stator windings may be compromised
Solution Approach 1:
The cooling circuit is segmented into separate loops: a first cooling circuit for the prime mover and a second cooling circuit for the electric machine stator. This segmentation allows each circuit to be optimized independently for its specific cooling requirements while maintaining overall system efficiency.
Solution Approach 2:
A heat exchanger serves as an intermediary component that transfers heat from the stator cooling circuit to the prime mover cooling circuit. This mediator enables effective heat removal from the stator windings while integrating the cooling systems and reducing overall complexity.
2Temperature
If multiple fluid types and loops are used for cooling different components, then heat removal effectiveness is improved, but system complexity and weight increase
Solution Approach 1:
The cooling system is divided into distinct cooling circuits for different components (prime mover and electric machine). Each circuit can use optimized fluid types and flow rates suited to its specific thermal requirements, maintaining cooling effectiveness while organizing complexity into manageable segments.
Solution Approach 2:
Heat exchangers act as intermediary components that enable thermal coupling between different cooling circuits. This allows multiple fluid types and loops to work together efficiently without requiring direct mixing or complex integration of all cooling pathways into a single system.
3Device complexity
If cooling fluid is supplied to both stator and bearings through the same circuit, then system simplicity is improved, but heat removal from stator windings may be reduced
Solution Approach 1:
The cooling system segments the cooling pathways: the second cooling circuit is dedicated specifically to stator winding cooling, while bearing cooling is handled separately. This ensures sufficient cooling fluid flow and heat removal capacity for the high-heat-generation stator windings while maintaining bearing lubrication and cooling.
Solution Approach 2:
The heat exchanger serves as an intermediary that allows the dedicated stator cooling circuit to effectively remove heat without competing directly with bearing cooling requirements for the same fluid flow resources.
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 reduces overall system weight and complexity by minimizing the number of fluid types and loops, effectively managing heat within the stator and bearings, while maintaining efficient lubrication and cooling, thus enhancing the performance and reliability of electric machines.
Implementation Method 1
The pump may move the cooling fluid through the stator portion(s) to remove heat from the stator windings via conduction
Implementation Method 2
The cooling circuit is also configured to supply the cooling fluid to bearings of the electric machine (e.g., rotor bearing(s)) to cool and/or lubricate the bearings
Data Source
AI summary
An example system comprises an electric machine including a stator and a rotor, a cooling system configured to supply a cooling fluid to cool the electric machine, and a stator tube configured to contain the cooling fluid within a stator portion of the electric machine and prevent the cooling fluid from contacting the rotor.