Parallel Gradient Coil Cable Layout for Low-Loss Flexibility
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Solution Overview
Problem
Conventional gradient cables in magnetic resonance imaging systems experience significant ohmic losses leading to heat buildup and temperature rise due to high current intensities, which is exacerbated by mechanical vibrations and limited cooling options.
Innovation Solution
A cable unit design featuring at least two parallel-connected cable elements for the feed line, with optional series-connected return line, allowing for higher current flow and reduced cross-sectional area per element, enhancing flexibility and cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single thick copper cable is used to reduce ohmic losses, then heat buildup is reduced, but the cable becomes less flexible and harder to install in constrained spaces
Solution Approach 1:
The patent divides the single thick cable into multiple parallel-connected cable elements (e.g., multiple copper bars or cables). Each element has a smaller cross-sectional area, maintaining flexibility while collectively providing the necessary current-carrying capacity to reduce ohmic losses. The parallel connection ensures equivalent electrical performance to a single thick cable while improving mechanical flexibility and ease of installation.
2Temperature
If cable cross-sectional area is increased to reduce heat buildup, then temperature rise is reduced, but the cable becomes more rigid and difficult to route through limited spaces
Solution Approach 1:
The cable system is segmented into multiple parallel elements, each with reduced individual cross-sectional area. This segmentation allows each element to remain flexible and easy to install, while the combined parallel structure provides sufficient total cross-sectional area to conduct high currents with minimal heat generation, thus controlling temperature rise.
Solution Approach 2:
Multiple cable elements are arranged in parallel and can be bundled together, with each element potentially containing nested conductors or being surrounded by insulation and protective layers. This nested arrangement allows flexible routing of individual elements while maintaining the integrity and current-carrying capacity of the complete cable assembly.
3Power
If high current intensity is transmitted through the cable, then power delivery to gradient coils is improved, but ohmic losses increase leading to heat buildup
Solution Approach 1:
The high current is divided and distributed across multiple parallel cable elements. By segmenting the current path into parallel conduits, the effective resistance is reduced (R_total = R/n for n parallel elements), thereby reducing ohmic losses (P_loss = I²R) while maintaining the ability to deliver high total power to the gradient coils.
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
Enables robust and flexible power supply to gradient coils, supporting high magnetic field gradients with faster rise and fall rates while minimizing temperature increase and facilitating easier installation in constrained spaces.
Implementation Method 1
The ohmic losses occurring in this process can lead to heat buildup in the gradient cable
Implementation Method 2
The ohmic losses occurring in this process can lead to heat buildup in the gradient cable. The temperature rise during the operation of the gradient coil unit increases with the current intensity in the gradient cable
Data Source
AI summary
A cable unit designed for connecting a gradient coil, which is embodied to generate a magnetic field gradient in one spatial direction, to a power amplifier, having at least one feed line, wherein the feed line comprises at least two cable elements at least in sections, and the at least two cable elements are connected electrically in parallel.