Fluid Cooled Magnetic Element with Segmented Coils
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Solution Overview
Problem
Magnetic elements such as transformers and inductors face limitations in power density due to heat transfer inefficiencies, which restrict current densities and electrical frequencies, leading to high eddy losses and size/cost challenges.
Innovation Solution
A fluid-cooled magnetic element design featuring a linear configuration of hollow cylindrical coils with alternating winding orientations and spacers, where cooling fluid flows through small gaps between the coils and spacers to enhance heat transfer, allowing for efficient cooling and high current densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If current density and electrical frequency are increased to minimize size and cost, then power density is improved, but heat generation increases proportionally to the square of current density and frequency, leading to heat transfer limitations
Solution Approach 1:
The magnetic element is divided into multiple discrete coils separated by spacers, creating segmented cooling channels between each coil-spacer interface. This segmentation allows cooling fluid to access multiple heat-generating surfaces simultaneously, improving overall heat transfer efficiency and enabling higher power densities without excessive temperature rise.
Solution Approach 2:
A liquid cooling system is implemented where cooling fluid is pumped through channels formed between coils and spacers. The hydraulic flow removes heat generated by high current densities and frequencies, allowing the system to operate at higher power levels by actively managing thermal dissipation through fluid circulation.
2Temperature
If conventional cooling methods are used, then device simplicity is maintained, but heat transfer efficiency is insufficient to support high current densities and frequencies
Solution Approach 1:
The spacers serve multiple functions simultaneously: they provide electrical insulation between adjacent coils, maintain mechanical spacing to create cooling channels, and structurally support the coil assembly. This multi-functionality integrates the cooling system into the existing structural framework, improving heat transfer efficiency without adding separate cooling components or increasing device complexity.
Solution Approach 2:
The cooling function is merged with the structural and insulating functions of the spacers. The same components that provide mechanical support and electrical isolation also define the cooling fluid pathways, consolidating multiple system functions into unified elements and avoiding the need for dedicated cooling structures.
3Volume of moving object
If coil spacing is reduced to minimize size, then volume is decreased, but heat transfer from winding and core becomes less efficient
Solution Approach 1:
Cooling fluid flow is introduced as a new dimension for heat removal, complementing conventional conduction and radiation pathways. The liquid coolant flows through the gaps between coils and spacers, providing an additional thermal management dimension that enables tighter coil packing while maintaining effective heat dissipation through forced convection.
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 achieves improved heat transfer efficiency, enabling high current densities and specific power levels, such as greater than 300 kW/kg at 20 kHz, while minimizing eddy losses and optimizing thermal impedance.
Implementation Method 1
Cooling fluid is directed through the gaps to cool the coils
Implementation Method 2
efficient heat transfer from the winding and core
Implementation Method 3
a contribution to a magnetic field at the center of the first coil, from a current flowing through both coils in series
Implementation Method 4
Cooling fluid is directed through the gaps to cool the coils
Data Source
AI summary
A fluid-cooled magnetic element. A plurality of coils is arranged in a non-toroidal configuration. Each coil may be a hollow cylinder, formed by winding a rectangular wire into a roll. The coils alternate with planer spacers. The coils may alternate in winding orientation, and the inner end of each coil may be connected, through a connection pin, to the inner end of an adjacent coil. Small gaps are formed between the coils and the spacers, e.g. as a result of each spacer having, on its two faces, a plurality of raised ribs, against which the coils abut. Cooling fluid flows through the gaps to cool the coils.