Fluid-Cooled PM Synchronous Rotor for Magnet Heat Dissipation
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Solution Overview
Problem
Existing electric machines face challenges in achieving a high power-to-weight ratio and efficient cooling, particularly in permanent magnet synchronous machines, leading to potential demagnetization and heat-related damage due to inadequate cooling systems.
Innovation Solution
A fluid-cooled, multiphase permanent magnet synchronous machine with a stator and rotor configuration that includes a heat-conducting layer extending from permanent magnet elements to the rotor shaft, featuring cooling fluid channels and a support structure for thermal energy transport, allowing for efficient heat dissipation in both internal and external rotor configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional cooling systems are used with stator jacket cooling and rotor cooling, then cooling capability is provided, but the power-to-weight ratio is limited and installation space increases
Solution Approach 1:
The patent combines the stator cooling and rotor cooling functions into a unified cooling system that shares common cooling channels and coolant circulation paths. The cooling medium flows continuously through both stator and rotor components, merging what were previously separate cooling systems into one integrated thermal management solution, thereby reducing overall system weight while maintaining cooling capability.
Solution Approach 2:
The cooling system is designed to serve multiple functions simultaneously: it cools the stator winding, cools the rotor permanent magnets, and provides structural support. The cooling channels are integrated into the magnetic circuit components themselves, making these components serve both magnetic and thermal management functions, thus improving power-to-weight ratio.
2Power
If permanent magnet elements are used in the rotor, then high power output is achieved, but heat generation leads to demagnetization risk
Solution Approach 1:
The patent introduces a thermally conductive layer as an intermediary between the permanent magnet elements and the cooling channels. This layer acts as a heat transfer mediator, conducting heat away from the magnets efficiently while allowing the magnets to maintain their positioning and magnetic properties. The intermediary layer enables effective thermal management without compromising the magnetic function.
Solution Approach 2:
The cooling system utilizes phase transition of the cooling medium (liquid to vapor and back) to enhance heat removal from the permanent magnets. The cooling channels are designed to facilitate this phase change process, which provides intensive cooling capability to prevent demagnetization while maintaining high power output.
3Temperature
If cooling channels are integrated into the rotor structure, then cooling efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The rotor is segmented into modular components with standardized cooling channel patterns. Each rotor module can be manufactured separately with integrated cooling channels, then assembled into the complete rotor assembly. This segmentation allows for simplified manufacturing of individual components while achieving efficient cooling in the final assembled structure.
Solution Approach 2:
The patent employs composite material construction for the rotor, combining magnetic materials with thermally conductive materials in a layered or integrated structure. This composite approach allows the cooling channels to be formed as part of the material structure itself rather than requiring separate machining operations, thereby improving cooling efficiency while managing manufacturing complexity.
4Weight of moving object
If high power-to-weight ratio is achieved, then compact design is possible, but cooling requirements increase leading to higher temperatures
Solution Approach 1:
The cooling system is designed to provide continuous cooling action throughout the operation of the motor. The cooling channels are positioned to ensure constant coolant flow through all high-heat-generation areas, and the thermally conductive layers maintain continuous thermal contact between heat sources and cooling paths. This continuous cooling action enables compact high power-to-weight design while controlling operating temperatures.
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 design achieves a high power-to-weight ratio and minimal installation space with effective cooling, reducing the risk of demagnetization and maintaining operational efficiency even at high speeds.
Implementation Method 1
at least one thermally conductive layer extends from the side of the permanent magnet elements and/or the rotor tooth elements furthest from the air gap to near the rotor shaft
Implementation Method 2
The rotor has cooling fluid channels penetrating it near the rotor shaft. The rotor shaft has cooling fluid supply and/or discharge lines connected to the rotor's cooling fluid channels.
Data Source
Figure 1
Figure 2
Figure 2a
AI summary
The invention relates to a fluid-cooled, multi-phase permanently excited synchronous machine, having a stator and a rotor in an outer-rotor or inner-rotor configuration. Here, the stator has field coils to be energised, and the rotor has permanent-magnet elements. The stator is spaced apart from the rotor radially, thus forming an air gap. The rotor is divided axially into two or more rotor discs sitting on a rotor shaft. Each rotor disc comprises two or more at least practically unmagnetic, preferably paramagnetic carrier plates supporting the permanent-magnet elements and soft-magnetic rotor tooth elements. A heat-conductive layer reaching from the permanent-magnet elements at least as far as close to the rotor shaft is received between the carrier plates. The rotor, close to the rotor shaft, has cooling fluid channels penetrating the carrier plates of the rotor lamination radially and axially. The rotor shaft has cooling fluid feed lines and/or discharge lines connected to the cooling fluid channels of the rotor.