Multi-PCM Cooling Device for Electrical Machine Winding Head Temperature Control
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Solution Overview
Problem
Electrical machines, particularly stator windings, face heat buildup issues due to inadequate cooling, leading to increased dielectric loss, reduced efficiency, and potential electrical breakdowns, as existing cooling methods are insufficient in managing high temperature peaks and long-term exposure limits.
Innovation Solution
A multi-stage cooling system utilizing a combination of phase change materials (PCMs) with distinct phase transition temperatures, along with detection and control mechanisms to trigger cooling measures, ensures effective heat management and temperature monitoring, preventing damage from critical temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If classical liquid coolant circulation systems are used, then heat can be transported and released at heat exchangers, but the system complexity increases and the cooling effectiveness in winding heads is insufficient
Solution Approach 1:
The patent utilizes the phase transition (melting/freezing) of phase change materials to absorb and release heat. The PCM melts during operation to absorb heat from the winding head, and freezes during idle periods to release heat, providing passive cooling without complex circulation systems. This directly addresses the contradiction by achieving effective temperature control through phase change while avoiding the complexity of pump-driven liquid coolant systems.
Solution Approach 2:
The cooling system is designed to be self-regulating through the natural phase transition properties of PCMs. The material automatically absorbs heat when temperature rises (melting) and releases heat when temperature drops (freezing), without requiring external control systems, pumps, or complex infrastructure. This self-service mechanism resolves the contradiction by providing effective cooling with minimal system complexity.
2Temperature
If thermosiphon cooling systems are used, then passive circulation occurs due to density differences, but the cooling effectiveness for high temperature peaks is insufficient
Solution Approach 1:
The patent employs phase change materials that undergo melting and freezing transitions to actively absorb and release heat. This phase transition mechanism provides much higher heat absorption capacity compared to thermosiphon systems, which rely on passive convection. The PCM can absorb large amounts of heat during melting, effectively addressing high temperature peaks and improving cooling efficiency significantly.
Solution Approach 2:
The system changes the thermal parameters by using materials with high latent heat of fusion. The PCM's ability to absorb large amounts of heat during phase transition fundamentally changes the heat transfer parameters, enabling effective cooling of high temperature peaks that thermosiphon systems cannot handle efficiently.
3Temperature
If heat pipe cooling systems are used, then heat is transported from heat source to heat sink, but the system requires hermetically sealed volumes and specific orientations
Solution Approach 1:
The patent uses phase change materials that melt and freeze to transfer heat, replacing heat pipe technology. This approach eliminates the need for hermetically sealed volumes, specific orientations, and complex internal structures required by heat pipes. The PCM simply absorbs heat during melting and releases it during freezing, providing effective heat transport with much simpler system structure.
Solution Approach 2:
The invention extracts the essential heat transfer function from heat pipes and implements it through phase change materials. By taking out the heat transport capability and implementing it through PCM melting/freezing, the system eliminates the complex hermetically sealed structures and orientation requirements of heat pipes, achieving the same thermal management with simpler construction.
4Temperature
If multiple phase change materials with different transition temperatures are used, then multi-stage cooling is achieved, but the device complexity increases
Solution Approach 1:
The patent divides the cooling function into multiple stages by using different PCMs with different melting points. Each PCM handles a specific temperature range, creating a segmented cooling system that provides comprehensive temperature control. This segmentation approach achieves wide temperature range coverage while keeping each individual PCM module relatively simple.
Solution Approach 2:
The system uses composite cooling by combining multiple phase change materials with different thermal properties and transition temperatures. This composite approach enables multi-stage cooling across different temperature ranges, achieving comprehensive temperature management. The combination of different PCMs provides enhanced cooling capability while maintaining manageable system complexity through modular design.
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
The PCM-based cooling system provides reliable and efficient heat dissipation across various temperature ranges, preventing material damage and extending the service life of electrical machines by managing temperature peaks and maintaining efficiency.
Implementation Method 1
a combination of at least two phase-change materials which exhibit a reversible, thermally inducible, endothermic phase transition at a phase-transition temperature
Implementation Method 2
utilize the liquid-gas phase change
Implementation Method 3
The medium, which evaporates endothermically at the heat source, is transported to the heat sink due to the vapor pressure gradient
Implementation Method 4
where it condenses and is then drawn back towards the heat source by capillary action
Implementation Method 5
the circulation of the cooling medium occurs passively due to the density difference between the liquid and gaseous medium
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
The invention relates to a cooling device (26) for cooling a component (14) of an electrical machine (10), for example a stator of an electric motor. The cooling device (26) comprises a combination of at least two phase change materials (PCMs) which have a reversible, thermally inducible, endothermic phase transition at a phase transition temperature (Ttr), a first phase transition temperature (Ttr1) of a first phase change material (28) being within a non-critical operating temperature range of the component to be cooled (14) and a second phase transition temperature (Ttr2) of a second phase change material (30) being above the first phase transition temperature (Ttr1).