Direct Winding Heat Exchanger for Electric Machine Thermal Management
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Solution Overview
Problem
The increasing demand for high torque density electric machines in applications such as hybrid electric vehicles and off-road construction equipment is hindered by thermal degradation of windings, which increases resistance and degrades insulation, necessitating improved cooling systems and manufacturing techniques.
Innovation Solution
The implementation of an electric machine with direct winding heat exchange, featuring a stator, rotor, and consolidated coils with integrated insulators, along with non-conductive bulkheads and heat exchangers that provide electric and fluid isolation, enhancing thermal management and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If higher power outputs are generated to meet increasing demand for electrical power sources, then power output increases, but thermal degradation of windings increases causing increased resistance and insulation degradation
Solution Approach 1:
The cooling system is segmented into multiple channels with bulkheads that divide the stator core into separate cooling zones. This allows independent temperature control in different regions, enabling higher power outputs without uniform thermal degradation across the entire winding structure.
Solution Approach 2:
A thermal coupling compound acts as an intermediary substance between the windings and cooling channels, facilitating efficient heat transfer from the windings to the cooling fluid while maintaining electrical isolation. This mediator enables higher power operation by effectively removing heat that would otherwise cause thermal degradation.
2Reliability
If conventional cooling systems are used, then manufacturing is simpler, but thermal management is insufficient leading to winding degradation
Solution Approach 1:
The cooling channels are merged with the stator core structure itself, eliminating the need for separate cooling housings or attachments. The bulkheads are integrated into the stator assembly, combining structural support and cooling functions into a single manufactured component, thereby improving thermal management without significantly increasing manufacturing complexity.
Solution Approach 2:
The bulkheads serve multiple functions: they provide structural support for the windings, create sealed cooling channels, facilitate heat transfer through thermal coupling, and enable modular assembly. This multi-functionality improves thermal management while avoiding the need for additional specialized components that would complicate manufacturing.
3Loss of energy
If direct winding heat exchange is implemented, then heat exchange efficiency improves, but device complexity increases due to integrated insulators and monolithic bodies
Solution Approach 1:
The insulator and coil are merged into a single monolithic body through co-molding or integral manufacturing processes. This integration eliminates the need for separate insulator components and assembly steps, thereby improving heat exchange efficiency through direct thermal contact while actually reducing device complexity by consolidating parts.
Solution Approach 2:
The monolithic body uses composite materials that provide both electrical insulation and thermal conduction properties. This allows direct winding heat exchange to be implemented without compromising electrical isolation, improving heat exchange efficiency while maintaining manageable structural complexity through material rather than geometric complexity.
4Reliability
If multiple bulkheads and sealing surfaces are added for electric and fluid isolation, then reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
Multiple sealing functions are merged into single bulkhead components that provide both electric isolation and fluid sealing simultaneously. The tapered channel design combines alignment and sealing functions in one geometric feature, reducing the number of separate precision surfaces needed while maintaining reliable isolation.
Solution Approach 2:
The bulkhead geometry uses tapered channels and specific surface angles that provide self-aligning and self-sealing properties during assembly. This reduces the precision requirements for sealing surfaces by using geometric parameters that compensate for manufacturing tolerances, while still achieving reliable electric and fluid isolation.
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 effectively addresses thermal degradation by improving heat exchange and manufacturing processes, leading to increased reliability, reduced costs, and enhanced performance of electric machines by maintaining torque density and reducing thermal issues.
Implementation Method 1
at least one heat exchanger thermally coupled to the at least one coil
Implementation Method 2
the first sealing surface is configured to provide electric and fluid isolation for a plate of the electric machine, the second sealing surface of the channel is configured to receive a distal end of the at least one heat exchanger and provide electric and fluid isolation for the heat exchanger
Data Source
AI summary
According to various aspects disclosed herein, exemplary embodiments of an electric machine with direct winding heat exchange is disclosed, including a stator, a rotor, at least one coil positioned on a stator tooth of the stator, with the coil comprising one or more turns of a conductor and an insulator, where the insulator and coil form a monolithic body having at least one facet at an angle that corresponds to the geometry of a stator slot of the stator. In addition the exemplary electric machine can include at least one heat exchanger thermally coupled to the at least one coil, at least one non-conducting bulkhead, the non-conducting bulkhead comprising a body made of a polymer, the body including a first sealing surface and a tapered channel, the channel including a second sealing surface, where the first sealing surface is configured to provide electric and fluid isolation for a plate of the electric machine, the second sealing surface of the channel is configured to receive a distal end of the at least one heat exchanger and provide electric and fluid isolation for the heat exchanger.