3D Magnetic Structures for Large-Air-Gap Transformer Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Large air gaps in power transformers reduce coupling efficiency, increase leakage inductance, and decrease mutual inductance, posing challenges in wireless power transfer systems.
Innovation Solution
The development of magnetic structures with increased air gap area through the use of magnetic ears and optimized winding configurations to minimize air gap reluctance, reduce leakage inductance, and shield windings from unwanted magnetic fields, thereby enhancing coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If large air gap is used in power transformer, then wireless power transfer distance is increased, but coupling efficiency decreases and leakage inductance increases
Solution Approach 1:
The patent transitions from conventional planar magnetic structures to three-dimensional C-shaped magnetic structures with vertical rods and lateral ears. This dimensional change creates multiple magnetic coupling paths (through the rod and through the ears) that simultaneously increase the effective coupling area and maintain strong magnetic coupling even at large air gap distances, thereby resolving the contradiction between increased transfer distance and maintained coupling efficiency.
Solution Approach 2:
The patent employs composite magnetic structures combining high-permeability magnetic materials (ferrite or silicon steel) in specific geometric configurations. The C-shaped structure with vertical rods and lateral ears creates a composite magnetic path that reduces reluctance and minimizes leakage flux, enabling efficient power transfer across large air gaps by optimizing the composite magnetic circuit geometry.
2Length of stationary object
If large air gap is used in power transformer, then wireless power transfer distance is increased, but mutual inductance decreases
Solution Approach 1:
The C-shaped magnetic structure introduces vertical dimension with rods extending upward, creating additional magnetic coupling paths that penetrate through the air gap. This three-dimensional configuration increases the effective overlapping area between primary and secondary magnetic fields, thereby maintaining high mutual inductance even when the horizontal air gap distance is large.
3Ease of manufacture
If conventional magnetic structures are used, then manufacturing is simple, but AC copper loss is high due to unshielded windings
Solution Approach 1:
The patent introduces magnetic ears as intermediary structures positioned between the windings and the external magnetic field. These ears act as shields that redirect unwanted magnetic flux away from the windings, reducing eddy current losses in the copper conductors. The ears are made of high-permeability magnetic material that provides a low-reluctance path for stray flux, thereby protecting the windings from harmful magnetic fields while maintaining manufacturing simplicity.
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 proposed magnetic structures effectively minimize air gap reluctance, reduce AC copper loss, and improve the overall efficiency of wireless power transfer systems by directing magnetic fields and minimizing leakage flux.
Implementation Method 1
The proposed magnetic structures effectively minimize air gap reluctance, reduce AC copper loss, and improve the overall efficiency of wireless power transfer systems by directing magnetic fields and minimizing leakage flux.
Implementation Method 2
Large air gaps exhibit a large magnetic path reluctance. Keeping the value of this reluctance small, determined the development of new magnetic structures and wireless power transformers.
Implementation Method 3
A method of transferring power at a large distance is defined as Inductive Power Transfer (IPT) which is achieved through mutual coupling in a similar manner to conventional tight coupled transformers.
Data Source
AI summary
New and Useful magnetic structures are provided. One feature of the magnetic structures is that they are configured to help minimize the air gap reluctance, improving the magnetic structure's coupling coefficient. Another feature is that reducing the windings AC impedance of a magnetic structure is produced by shielding the winding under ears formed of magnetic material. Still another feature is that leakage inductance of a magnetic structure is reduced, by making ears with cuts which converge toward the magnetic rods that are used in the formation of the structure.