Stacked Lamination Inductor with Air Gap Spacers
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Solution Overview
Problem
Conventional inductors for high power motor controllers in aerospace applications face challenges in maintaining stable inductance at high currents and frequencies while minimizing weight and heat generation due to magnetic core eddy currents and stray magnetic fields, with existing solutions either increasing weight or generating unwanted magnetic fields.
Innovation Solution
A cut core inductor assembly with multiple air gap spacers and a thermally conductive mounting frame that separates magnetic core sections, allowing efficient heat conduction and minimizing eddy current losses by creating a high reluctance path and using thermally conductive materials to manage thermal energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional gapped tape-wound cut core inductors are used, then inductance stability at high currents is achieved, but eddy current losses increase and heat generation occurs at air gaps
Solution Approach 1:
The magnetic core is divided into multiple discrete laminations (e.g., 30 laminations) stacked together with insulation between layers. This segmentation interrupts the eddy current paths, reducing eddy current losses while maintaining the magnetic core's functional integrity and inductance stability.
Solution Approach 2:
The patent uses laminated magnetic core construction with intentional insulation layers between laminations, creating a layered porous structure that blocks eddy current circulation paths. This allows the magnetic field to pass through while preventing large-scale eddy currents, thereby reducing energy losses.
2Loss of energy
If powder magnetic core materials with distributed air gaps are used, then eddy current losses are reduced, but effective permeability drops significantly at high DC magnetizing forces
Solution Approach 1:
The patent changes the physical parameters of the magnetic core by using continuous magnetic laminations with controlled insulation rather than powder materials. This maintains high effective permeability at operating magnetizing forces while still reducing eddy current losses through the laminated structure's interrupted current paths.
3Power
If the number of coil turns is reduced to maintain inductance, then current handling capability improves, but powder core permeability becomes unacceptable
Solution Approach 1:
The patent employs a composite magnetic core structure combining multiple magnetic laminations with insulation layers, creating a composite material that maintains high permeability characteristics while enabling reduced coil turns for high current applications. The composite structure preserves magnetic field concentration better than powder cores.
4Loss of energy
If ferromagnetic core is eliminated to reduce heat at air gaps, then air gap losses are eliminated, but inductor size and mounting footprint increase significantly
Solution Approach 1:
The patent uses laminated magnetic core construction that eliminates or minimizes air gaps while maintaining reduced eddy current losses. The closely stacked laminations with thin insulation create a dense magnetic path that concentrates the magnetic field within a compact volume, reducing both losses and mounting footprint compared to air core designs.
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 solution effectively reduces eddy current losses and maintains desired inductance levels while facilitating efficient heat conduction, addressing the weight and thermal management issues in aerospace applications.
Implementation Method 1
Thermal energy removed from the magnetic core is communicated to the mounting frame
Implementation Method 2
Air gaps in the magnetic path create a high reluctance path, avoiding saturation of the magnetic field at lower frequencies
Implementation Method 3
An electric current travels through the inductor assembly generating a magnetic field and thermal energy
Implementation Method 4
An electric current travels through the inductor assembly generating a magnetic field and thermal energy
Data Source
AI summary
A power inductor assembly includes and multiple coil sections disposed upon a mounting frame. Multiple winding sections each encircle one of the multiple core sections and a portion of the mounting frame. Air gap spacers separate adjacent core sections. The arrangement facilitates removal of thermal energy from the magnetic core. Lamination build direction normal to inductor mounting surface minimizes eddy current losses.