Magnetically Permeable Core for Inductive Power Transfer
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Solution Overview
Problem
Current inductive power transfer (IPT) systems face challenges in maintaining efficient power transfer over large air gaps due to magnetic flux leakage, leading to low magnetic coupling coefficients and increased size and cost for a given power transfer capacity, particularly in applications with limited physical space such as rotary applications and wind power pitch control.
Innovation Solution
The use of magnetically permeable U cores with reduced limb lengths and increased number of turns within the same physical dimensions, which enhances the magnetic coupling coefficient by reducing leakage flux areas and accommodating more turns, thereby improving the magnetic field coupling and mutual inductance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetically permeable elements are introduced to increase inductance and shape the magnetic field, then the coupling factor between transmitter and receiver is improved, but magnetic flux leakage between the limbs of the cores increases, resulting in low magnetic coupling coefficient for large air gaps
Solution Approach 1:
The core is divided into multiple limbs (first limb, second limb, third limb, fourth limb) with windings on specific limbs. This segmentation allows the magnetic flux to be distributed and directed through specific paths, reducing leakage flux between limbs while maintaining high coupling coefficient even with large air gaps.
Solution Approach 2:
Different limbs of the core have different properties - some limbs have windings while others serve as flux paths. The core structure is designed with specific local characteristics (winding locations, limb configurations) to optimize magnetic flux distribution and minimize leakage, improving coupling without increasing energy loss.
2Volume of moving object
If the physical space is reduced for compact design, then the system size is decreased, but the air gap is reduced, causing increased magnetic flux leakage within the core limbs
Solution Approach 1:
The segmented core structure with four limbs allows compact arrangement while maintaining adequate flux paths. The segmentation enables the core to be configured in a space-efficient manner without compromising the magnetic coupling, as each limb serves a specific function in the magnetic circuit.
Solution Approach 2:
The core structure utilizes three-dimensional spatial arrangement of limbs and windings to achieve compact design. By optimizing the spatial configuration and utilizing vertical and horizontal dimensions effectively, the design maintains high coupling coefficient while reducing overall assembly size.
3Reliability
If the number of coil turns is increased to achieve the same inductance without magnetically permeable elements, then the inductance value is maintained, but the device complexity and size increase
Solution Approach 1:
The introduction of magnetically permeable core material changes the magnetic properties of the system, significantly increasing the inductance for a given number of turns. This parameter change allows reduction in the number of required coil turns while maintaining the same inductance value, simplifying the device structure.
Solution Approach 2:
The combination of magnetically permeable core material with coil windings creates a composite structure that leverages the high permeability of the core to concentrate and direct magnetic flux. This composite approach achieves high inductance with fewer turns 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
This configuration achieves a 13% to 23% improvement in magnetic coupling coefficient, resulting in increased efficiency, a more compact design, and reduced costs without increasing the size of the coil assemblies, while maintaining high flux linkage even with large air gaps.
Implementation Method 1
a primary coil, to which a current is applied, is wound; and a secondary core having a width wider than a width of the primary core, and receiving a secondary coil which outputs a current generated by a magnetic field, wherein the magnetic field is induced by the primary coil to the secondary coil
Implementation Method 2
Magnet ically permeable elements can also be configured to 'shape' the magnetic field, which can be directed from the transmitter to the receiver. By directing the magnetic field, the coupling factor between the transmitter and receiver can be increased
Implementation Method 3
Magnet ically permeable elements increase the inductance of the transmitter or receiver coils
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
An inductive power transfer coil assembly including: a magnetically permeable core including a base having a pair of spaced apart limbs extending therefrom; and a winding located between and above the pair of spaced apart limbs.