Stator Cooling Ducts and Wind Caps for Electric Machines
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Solution Overview
Problem
Electric machines face efficiency reductions due to heat generation in stators and rotors, leading to demagnetization and thermal fatigue, which affects performance and output power, particularly in vehicles where thermal limits are exceeded.
Innovation Solution
The implementation of a stator cooling system with cooling ducts and wind caps that distribute a coolant around the stator windings, allowing for efficient heat dissipation and minimizing thermal stress, using copper windings and strategically placed outlets to optimize coolant flow and reduce the required coolant volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If oil cooling is used for the rotor, then cooling efficiency is improved, but the stator cooling becomes more complicated
Solution Approach 1:
The stator cooling system is segmented into multiple independent cooling ducts distributed around the stator circumference, with separate inlet and outlet paths. This segmentation allows simplified individual duct designs while achieving comprehensive cooling coverage, resolving the contradiction between cooling efficiency and system complexity.
Solution Approach 2:
The cooling ducts serve multiple functions simultaneously: they cool the stator windings, structurally support the stator assembly, and provide thermal pathways for heat dissipation. This multi-functionality reduces the need for separate cooling components, simplifying the overall stator cooling system while maintaining effective temperature control.
2Temperature
If coolant volume is increased, then cooling performance is improved, but device size and cost increase
Solution Approach 1:
Coolant flow distribution is optimized with local quality variations - higher flow rates are directed to regions with highest heat generation (end windings and slot regions), while lower flow rates suffice in cooler areas. This localized flow optimization achieves effective cooling performance with reduced total coolant volume, preventing both overheating and excessive system size.
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 performance and energy efficiency of electric machines by effectively managing temperature, reducing the risk of demagnetization and thermal fatigue, while also providing cost savings through the use of plastic or metal wind caps with coatings for insulation.
Implementation Method 1
cooling ducts connected to the inlet and extending though the plurality of windings
Implementation Method 2
a coolant flows from the inlet to the wind cap through the cooling ducts
Implementation Method 3
The wind caps encapsulate each of end windings such that a coolant flows from the inlet to the wind cap through the cooling ducts
Data Source
AI summary
An electric machine including a housing, a movable element within the housing, a stator surrounding the movable element within the housing, the stator including a plurality of windings with end windings at a first end and a second end, and a stator cooling system including an inlet through the housing, cooling ducts connected to the inlet and extending though the plurality of windings, and a wind cap at each of the first end and the second end of the end windings, encapsulating each of end windings such that a coolant flows from the inlet to the wind cap through the cooling ducts, wherein each wind cap includes at least one outlet. The present disclosure further relates to a method of cooling an electric machine.