Toroidal Power Coupling Shielding for Low RF Leakage
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Solution Overview
Problem
Existing power coupling devices for CT scanners and similar applications face issues with RF emission, increased leakage inductance, and reduced efficiency due to inadequate shielding, especially when power is transferred between rotating and stationary parts.
Innovation Solution
A shielded power coupling device with an axisymmetric solid of revolution design, featuring toroidal windings and half-shields with electrically conductive material to cancel magnetic flux, reducing RF emission and leakage inductance while improving efficiency by aligning magnetic flux loops in meridional planes and using fringe field canceling zones to prevent fringing fields from escaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a complete Faraday cage shield is used to surround the power coupling device, then RF emission and electromagnetic interference are reduced, but relative rotation between stationary and rotating subsystems is blocked
Solution Approach 1:
The shield is divided into multiple separate segments rather than forming a complete enclosure. Each segment is positioned to provide shielding in specific directions while leaving gaps that permit rotational movement. The segments are electrically connected through conductive pathways that maintain shielding effectiveness while allowing mechanical rotation.
Solution Approach 2:
Different regions of the shield structure have different properties: certain areas have continuous conductive shielding material to block RF emission, while other regions have gaps or reduced shielding to permit rotation. The shield provides localized protection where needed while maintaining mechanical flexibility elsewhere.
2Adaptability or versatility
If shield segments are separated to permit rotation, then relative movement is enabled, but shielding effectiveness is reduced due to gaps
Solution Approach 1:
Conductive material serves as an intermediary element that bridges shield segments. This conductive material creates electrical pathways that maintain the shielding effect across segment boundaries, allowing RF currents to flow continuously around gaps while still blocking electromagnetic interference from escaping or entering the power coupling device.
Solution Approach 2:
The shielding approach transitions from a two-dimensional planar shield to a three-dimensional segmented structure with conductive pathways extending in multiple directions. The conductive material creates electrical connections that wrap around gaps, effectively extending the shielding surface into additional spatial dimensions to maintain continuity despite physical separations.
3Object-affected harmful factors
If traditional shielding structures are used, then RF emission is reduced, but leakage inductance increases and efficiency decreases
Solution Approach 1:
The shield geometry parameters are optimized to balance shielding effectiveness with electromagnetic performance. Specific parameters such as segment spacing, conductive pathway dimensions, and shield positioning are adjusted to minimize leakage inductance while maintaining RF emission reduction. The conductive material configuration is tuned to create optimal electromagnetic field distribution that reduces energy losses.
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 RF emission and leakage inductance, enhancing the efficiency of power transfer in CT scanners and similar applications by canceling magnetic flux and preventing fringing fields from escaping, thus improving the overall performance of the power coupling device.
Implementation Method 1
half-shields with electrically conductive material to cancel magnetic flux
Implementation Method 2
inductively transfer electric power
Data Source
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AI summary
Axisymmetric solid of revolution derivable from section at FIG. 5 is generally toroidal with electric current(s) in windings 110, 160 preferably flowing circumferentially along major circle(s) during power coupling device operation. Current(s) in windings 110, 160; current(s) in half-shields 120, 170; and the volume of space swept out by shield airgap(s) 101 emerge from plane of paper perpendicularly at FIG. 5 but as these emerge therefrom they curve to follow toroidal major circle(s). Cores 115, 165 preferably shunt and align magnetic flux such that magnetic field lines escape therefrom primarily only in region(s) of core airgap(s) and such that magnetic flux loops lie in planes of toroidal minor circle(s). Half-shield(s) 120, 170 preferably have electrically conductive material(s) distributed therein as is sufficient to substantially cancel magnetic flux lines impinging thereon before effects of such impinging magnetic flux lines would reach shield airgap(s) 101 and/or outer surface(s) of half-shields 120, 170.