Phase Connection Box Cooling for End-Winding Hotspot Reduction
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Solution Overview
Problem
The connection between the end windings of a stator coil winding and a busbar in an electric drive system experiences significant temperature increases due to reduced cross-sectional area during welding, leading to localized 'hotspots' that affect performance and efficiency.
Innovation Solution
A thermal connection using multiple layers of copper and ceramic plates to conduct heat away from the hotspot, integrated with the phase connection box housing, facilitated by oil interaction and forced air convection for temperature regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If direct oil cooling is applied to the phase connection box, then hotspot temperature is reduced, but oil wetting and chemical reactions occur
Solution Approach 1:
The cooling system is segmented into two separate parts: the reducer housing containing cooling oil and the phase connection box housing containing the electrical components. The thermal connection plate conducts heat from the phase connection box to the reducer housing, allowing indirect cooling without direct oil contact with electrical components, thus preventing oil wetting and chemical reactions while still reducing hotspot temperature
Solution Approach 2:
The thermal connection plate acts as an intermediary between the phase connection box and the cooling oil. It conducts heat away from the hotspot indirectly through the housing structure, enabling thermal management without direct fluid contact with sensitive electrical components, thereby maintaining system reliability
2Reliability
If welding is performed to connect end windings to busbar, then electrical connection is achieved, but cross-sectional area is reduced causing increased ohmic losses
Solution Approach 1:
The invention changes the thermal parameter (temperature) at the welding point by introducing active cooling through the thermal connection plate. By reducing the temperature at the hotspot, the electrical resistance of the welded connection is reduced, thereby decreasing ohmic losses while maintaining the reliable electrical connection achieved through welding
3Loss of energy
If thermal connection is implemented to reduce hotspot temperature, then ohmic losses are reduced, but device complexity increases
Solution Approach 1:
The thermal connection plate is merged with the existing housing structure of the phase connection box and reducer housing. By integrating the cooling function into the existing structural components rather than adding separate cooling apparatus, the invention reduces ohmic losses through active cooling while minimizing the increase in device complexity
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
Reduces hotspot temperatures, minimizing ohmic losses and enhancing system efficiency by effective heat extraction through conductive and convective means.
Implementation Method 1
The copper layer is in contact with each end winding in proximity to the hotspot... to provide conduction heat extraction from the hot spot
Implementation Method 2
the ceramic layer is in contact with the connection box housing... disposed between and in contact with the first copper layer and the second copper layer
Implementation Method 3
the heat extraction from the housing of the phase connection box takes place through the interaction between the oil and the housing of the phase connection box
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The present invention relates to a thermal connection for an electric drive system (10), having at least one copper layer (38,42), at least one ceramic layer (40) in contact with the copper layer (38,42), a coil winding being part of the electric drive system (10), the coil winding having a plurality of wires (30a,30b), a hotspot located at an end winding of each of the plurality of wires (30a,30b), a busbar (34a) connected to each end winding in proximity to the hotspot, and a connection box housing (32), each end winding and the busbar (34a) located in the connection box housing (32). The copper layer (38,42) is in contact with each end winding in proximity to the hotspot, and the ceramic layer (40) is in contact with the connection box housing (32). A second copper layer (42) is in contact with the connection box housing (32) such that the ceramic layer (40) is disposed between the copper layer (38) and the second copper layer (42). The connection box housing (32) is part of a housing (46) of a reducer (14).