Permanent Current Switch Circuit for MRI Quench Reliability
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Solution Overview
Problem
Magnetic resonance imaging (MRI) systems with superconducting magnets face challenges in maintaining a stable magnetic field due to quench events and heater connectivity issues, leading to operational failures and reduced reliability.
Innovation Solution
A permanent current switch apparatus with thermal permanent current switches connected in parallel and series, utilizing heaters and a heater connecting wire to manage current flow and maintain the superconducting state, ensuring redundancy and reliability by equalizing current distribution and handling quench events effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If thermal permanent current switches are connected in parallel without series parallel structures, then the switching capability is improved, but the reliability during quench events deteriorates
Solution Approach 1:
The patent divides the parallel switch structure into multiple series-connected parallel structures. Each parallel structure contains thermal permanent current switches connected in parallel, and these parallel structures are connected in series. This segmentation allows the system to maintain switching capability while improving reliability during quench events, as a quench in one parallel structure does not affect the others due to the series connection.
Solution Approach 2:
The patent implements redundancy by having multiple thermal permanent current switches in parallel within each parallel structure. This beforehand cushioning ensures that if one switch fails or undergoes a quench event, the other switches in the parallel structure can continue to function, thereby maintaining system reliability and protecting against operational failures.
2Device complexity
If heaters are connected without parallel grouping, then the circuit simplicity is improved, but the current distribution uniformity deteriorates
Solution Approach 1:
The patent segments the heater circuit into multiple groups, with heaters connected in parallel within each group. This segmentation ensures that the current flowing through each heater is equal and uniform, while the grouped parallel structures maintain relative circuit simplicity. The parallel grouping within each group allows for balanced current distribution across all heaters.
3Device complexity
If single parallel connection is used, then the device complexity is reduced, but the redundancy and reliability deteriorate
Solution Approach 1:
The patent employs a segmented architecture with multiple parallel structures connected in series, where each parallel structure contains multiple thermal permanent current switches in parallel. This segmentation creates a balanced complexity that provides redundancy and reliability without excessive device complexity, as each segment can operate independently.
Solution Approach 2:
The patent implements beforehand cushioning through redundant thermal permanent current switches in parallel within each parallel structure. This redundancy ensures that if one switch fails, the system can continue to operate with the remaining switches, thereby improving reliability without adding excessive complexity to the overall device.
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 enhances the reliability of MRI systems by maintaining the superconducting state during quench events and ensuring continuous operation, with improved redundancy and reduced unreliability compared to previous designs, while also addressing heater connectivity issues.
Implementation Method 1
a heater; and a switch part configured to switch the thermal permanent current switch between a superconducting state and a normal conducting state by heat emitted by the heater
Implementation Method 2
the superconducting coil has an electrical resistance of 0, and as a result, a large current can flow therethrough
Data Source
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AI summary
A permanent current switch apparatus (16, 216) according to an embodiment is a permanent current switch apparatus electrically connected to a superconducting coil (13) via a superconducting wire (163, SU), the permanent current switch apparatus including a plurality of parallel structures (JP1, JP2, JP3, JP4) with thermal permanent current switches (160, PC1-PC8) connected in parallel, the thermal permanent current switches (160, PC1-PC8) being capable of switching between conducting and interrupting an electric current flowing through the superconducting wire (163, SU). The parallel structures (JP1, JP2, JP3, JP4) are connected in series.