Segmented Cooling Plate for Electric Machine Winding Head Heat Removal
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Solution Overview
Problem
High-power electric machines in motor vehicles face heat removal challenges due to eddy currents induced in conductive cooling plates by the magnetic rotating field, which impede cooling and reduce continuous load capacity.
Innovation Solution
A segmented cooling plate with recesses filled with insulating material is used, positioned on the inner circumference of the winding head, reducing eddy currents and allowing closer proximity to the winding head for enhanced heat dissipation, and is thermally connected to the housing for efficient heat removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a conductive cooling plate is used for heat removal, then heat dissipation efficiency is improved, but eddy currents are induced which impede cooling and reduce effectiveness
Solution Approach 1:
The cooling plate is divided into multiple segments separated by insulating material (e.g., plastic strips or air gaps). This segmentation interrupts the continuous conductive path, preventing large-scale eddy current loops while maintaining localized thermal contact with the winding head for effective heat removal from hot spots.
Solution Approach 2:
The cooling plate features non-uniform thermal conductivity distribution - highly conductive regions contact the winding head for efficient heat extraction, while insulating regions (segments or gaps) are positioned to interrupt eddy current paths. This creates different functional zones within the same component.
2Temperature
If the cooling plate is positioned closer to the winding head, then heat dissipation is enhanced, but eddy currents increase due to stronger magnetic field coupling
Solution Approach 1:
By segmenting the cooling plate and positioning segments close to the winding head, the patent achieves both goals: close proximity enables efficient conductive heat transfer from hot spots, while segmentation interrupts eddy current paths that would otherwise be induced by the strong magnetic field coupling at close distances.
Solution Approach 2:
Insulating material acts as an intermediary between the cooling plate segments and the magnetic field environment. This intermediary allows thermal contact while electrically isolating segments to prevent eddy current formation in the high magnetic field region near the winding head.
3Reliability
If encapsulation material is used to fix coil windings, then mechanical and electrical protection is provided, but thermal insulation increases causing the winding head to become a hot spot
Solution Approach 1:
The cooling plate serves as a thermal intermediary between the encapsulated winding head and the housing/external cooling system. It conducts heat away from the encapsulated region through direct thermal contact, counteracting the insulating effect of the encapsulation material and preventing hot spot formation.
Solution Approach 2:
The encapsulation material may incorporate thermally conductive fillers or porous structures that provide both mechanical protection and enhanced thermal pathways, allowing heat to escape from the encapsulated winding head region while maintaining structural integrity and electrical insulation.
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 improves heat removal from the winding heads, reducing power losses and increasing the continuous load capacity of the electric machine, thereby enhancing drive power and service life.
Implementation Method 1
The encapsulation material is, along an outer circumference of the winding head, in thermal contact with the housing. A segmented cooling plate is arranged on an inner circumference of the encapsulated winding head.
Implementation Method 2
the magnetic rotating field of the rotating-field winding generates eddy currents in the electrically conductive surfaces of the cooling plate and of the housing, which eddy currents in turn act as additional heat sources
Data Source
AI summary
An electric machine has a housing and has a stator inside the housing, surrounding a rotor arranged on a motor shaft so as to be fixed to the shaft. A rotary field winding, at the ends of the stator, forms a winding head. The winding heads are embedded in a thermally conductive encapsulation material, wherein the encapsulation material is in thermal contact with the housing along the outer circumference of the winding head. A segmented cooling plate is arranged on the inner circumference of the encapsulation winding head.