Coreless Rotating Machine Cylindrical Coil Cooling
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Solution Overview
Problem
The temperature rise within coreless rotating electrical machines due to copper loss and eddy currents in cylindrical coils leads to efficiency deterioration and heat-induced degradation of permanent magnets, which existing cooling methods have not adequately addressed.
Innovation Solution
A coreless rotating electrical machine design featuring a cylindrical coil with a laminate structure and a cooling method that involves arranging the rotor with a cup-shape mount and magnets, allowing for direct cooling of both surfaces of the cylindrical coil and magnets through an air gap, using a lid-type mount and cup-type mount configuration to intake and discharge cooling medium or air, enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If cooling means is not provided, then device complexity is reduced, but temperature rise occurs leading to efficiency deterioration and magnet degradation
Solution Approach 1:
The cooling channels are integrated into the stator yoke structure itself, merging the cooling function with the structural component. This eliminates the need for separate cooling devices while effectively removing heat from the cylindrical coil and permanent magnets, thereby maintaining efficiency without increasing overall device complexity.
Solution Approach 2:
Cooling medium (air or fluid) is introduced as an intermediary substance to transfer heat away from the cylindrical coil and permanent magnets. The cooling medium flows through channels in the stator yoke, absorbing heat and carrying it away, thus protecting the magnetic components from thermal degradation while maintaining system efficiency.
2Temperature
If cooling medium is introduced to cool cylindrical coil, then temperature rise is reduced, but device complexity increases due to additional cooling structure
Solution Approach 1:
The cooling channels are merged with the stator yoke structure, so the cooling function is embedded within the existing structural component rather than being added as a separate system. This integration approach reduces the overall device complexity while still achieving effective cooling of the cylindrical coil and permanent magnets.
Solution Approach 2:
The stator yoke serves multiple functions: it provides structural support, creates the magnetic circuit, and houses the cooling channels. This multi-functionality eliminates the need for dedicated cooling structures, reducing device complexity while maintaining effective temperature control of the cylindrical coil and magnets.
3Force
If permanent magnets are equipped on rotor, then magnetic field strength is increased, but heat-induced coercive force deterioration occurs
Solution Approach 1:
Cooling medium flows through channels in the stator yoke, acting as an intermediary heat transfer substance. The cooling medium absorbs heat from the permanent magnets on the rotor through the stator structure, preventing heat-induced coercive force deterioration while maintaining strong magnetic field strength for high torque output.
Solution Approach 2:
The patent replaces passive thermal management with active cooling through structured channels. Instead of relying on natural convection or radiation, the system uses directed fluid flow through engineered channels to actively remove heat from the permanent magnets, ensuring coercive force stability even at high operating temperatures.
4Power
If rotational speed is increased, then power output is increased, but temperature rise accelerates
Solution Approach 1:
The cooling medium flows continuously through the channels in the stator yoke, providing continuous heat removal. This continuous cooling action ensures that even at high rotational speeds where heat generation is intense, the temperature rise is controlled and power output can be sustained without thermal limitations.
Solution Approach 2:
Cooling medium serves as an intermediary heat transfer substance that continuously absorbs heat generated during high-speed operation. The fluid flow through the stator yoke channels carries away thermal energy, enabling the system to maintain acceptable temperatures even when operating at high power levels and rotational speeds.
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 design effectively reduces temperature rise and maintains efficiency by ensuring thorough cooling of the cylindrical coil and magnets, even at higher rotational speeds, thereby preventing coercive force deterioration and increasing output.
Implementation Method 1
feeding or intaking cooling medium or cooling air to an air gap formed in an inner surface of the cylindrical coil; and directly cooling an inner surface and outer surface of the cylindrical coil as well as the magnets 4 equipped in the air gap
Implementation Method 2
directly cooling both surfaces of the cylindrical coil and magnets through an air gap
Data Source
AI summary
A high performance rotating electrical machine which aims at downsizing, and challenges inevitable technical problems such as deterioration of efficiency η caused by copper loss and temperature rise inside the rotating electrical machine due to heat generation induced by eddy current generated in magnetic body.