Rotating Device Wireless Power Transfer With Ferrite Shielding
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Solution Overview
Problem
Existing systems for wirelessly supplying rotating devices with electrical energy face challenges in minimizing geometry-based impacts and external electromagnetic interferences, particularly in high-speed applications like engine test benches, where changes in geometry and thermal expansion affect efficiency and stability, and external fields induce parasitic voltages.
Innovation Solution
A system featuring a flange disk with a disk-shaped ring and U-shaped ferrite core, embedded in a plastic filling with a MU metal ring, which provides shielding and maintains constant electromagnetic coupling, reducing external interference and geometry-related fluctuations by optimizing the magnetic energy flow and positioning of the ferrite core sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the distance between transmitting and receiving coils is increased, then the installation space is improved, but the energy transfer efficiency deteriorates due to increased electromagnetic stray flow
Solution Approach 1:
A ferrite core is introduced as an intermediary component between the transmitting and receiving coils. The ferrite core guides and concentrates the magnetic flux, creating a defined magnetic circuit that reduces electromagnetic stray flow while allowing increased distance between coils. This mediator enables both improved installation space and maintained energy transfer efficiency.
2Reliability
If electronic compensation circuits are added to compensate for geometry changes, then the energy transfer stability is improved, but the device complexity increases
Solution Approach 1:
The ferrite core is segmented into multiple sections (first ferrite section, second ferrite section, third ferrite section) with different geometries and positions. Each segment serves a specific function in guiding and concentrating magnetic flux in different regions of the magnetic circuit. This segmentation provides geometric compensation without requiring electronic circuits, as the physical structure itself compensates for alignment variations.
Solution Approach 2:
The ferrite core sections have different cross-sectional areas and positions, creating a magnetic circuit with varying reluctance characteristics. This geometric parameter variation in the ferrite structure provides passive compensation for changes in coil alignment and distance, maintaining energy transfer stability without electronic control.
3Volume of moving object
If the receiving coil is placed closer to the rotation axis, then the space utilization is improved, but the susceptibility to external electromagnetic fields increases
Solution Approach 1:
The ferrite core acts as a magnetic shield and intermediary, concentrating the magnetic flux between the transmitting and receiving coils. This creates a defined magnetic circuit that isolates the receiving coil from external electromagnetic fields while allowing it to be positioned in the space-constrained region near the rotation axis.
4Loss of energy
If the air gap between transmitting coil and receiving coil is reduced, then the energy transfer efficiency is improved, but the sensitivity to thermal expansion and manufacturing tolerances increases
Solution Approach 1:
The ferrite core serves as a thermal and magnetic intermediary between the transmitting and receiving coils. It provides a stable magnetic circuit with lower reluctance that is less sensitive to small variations in air gap distance caused by thermal expansion or manufacturing tolerances, maintaining energy transfer efficiency while reducing sensitivity to dimensional changes.
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 robust shielding against external electromagnetic fields and maintains consistent energy transfer even with axial and radial displacements, enhancing the reliability and efficiency of energy supply to rotating devices.
Implementation Method 1
When a voltage is applied to an induction coil system that is in an inductive operative connection with the ferrite core, a magnetic energy flow is formed between the end face of the short section and the end face of the long section of the ferrite core
Implementation Method 2
Another source of interference are external electromagnetic fields that can act on the receiving coil and thereby induce undesired parasitic voltages
Data Source
AI summary
A system for wirelessly supplying electric energy to a rotating device includes a flange disk, a disk-shaped ring, an annular plastic filling, a receiving coil which is embedded in the annular plastic filling, a U-shaped ferrite core having a short section, the end face of which is directed to the plastic filling, a long section which is oriented parallel to the short section and which extends parallel along the outer surface of the annular plastic filling, with the sections connected to one another via a section, a coil system and a receiving coil made of revolving wire windings. A distance of the end face of the long section from the rotation axis of the flange disk is smaller than a distance of the receiving coil from the rotation axis of the flange disk.