MRI-Compatible SMPS Using Air-Core Inductors and Frequency Shifting
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Solution Overview
Problem
Conventional MRI systems face challenges in providing efficient power conversion near RF receivers without affecting image quality due to noise and magnetic field compatibility issues with existing power supply technologies, leading to complex wiring and inefficiencies.
Innovation Solution
A switched mode power supply (SMPS) using air core magnetic energy storage components operates at a switching frequency that generates electromagnetic interference outside the MRI system's imaging bandwidth, eliminating EMI noise and allowing placement near the magnet, thereby simplifying power distribution and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional SMPS designs are used in MRI systems, then power delivery efficiency is improved, but electromagnetic interference noise affects image quality
Solution Approach 1:
The patent changes the switching frequency parameter to 3.3 kHz, which is specifically selected to fall outside the MRI imaging bandwidth. This parameter modification allows the SMPS to maintain high efficiency while ensuring that electromagnetic interference occurs at frequencies that do not degrade image quality
Solution Approach 2:
The patent employs dynamic switching control where the SMPS operates only when no imaging is正在进行, and the switching frequency is dynamically selected to avoid the imaging bandwidth. This dynamic operation allows the system to achieve both high efficiency and EMI-free operation during imaging
2Use of energy by moving object
If ferromagnetic energy storage components are used in SMPS, then power conversion efficiency is improved, but the components cannot operate in the vicinity of the MRI magnet due to magnetic field saturation
Solution Approach 1:
The patent uses non-ferromagnetic materials (such as air-core inductors or inductors with non-ferromagnetic cores) to construct the energy storage components. These materials do not exhibit magnetic saturation in the presence of strong magnetic fields, allowing the SMPS to operate efficiently in close proximity to the MRI magnet without performance degradation
3Object-affected harmful factors
If linear regulators are used in scan room power supply, then electromagnetic interference noise is reduced, but power delivery efficiency deteriorates and heat management becomes complex
Solution Approach 1:
The patent employs periodic switching action characteristic of SMPS, where power conversion occurs in discrete switching cycles at 3.3 kHz. This periodic operation enables high efficiency power conversion while the switching frequency is specifically chosen to avoid generating EMI within the MRI imaging bandwidth, unlike continuous operation of linear regulators
4Object-affected harmful factors
If the scan room power supply is located away from the magnet, then magnetic field interference is avoided, but wiring complexity and power loss increase
Solution Approach 1:
The patent extracts the SMPS from the equipment room and relocates it inside the scan room near the magnet. By using non-ferromagnetic energy storage components, the design eliminates the constraint that previously required separation, thereby removing the need for long wiring runs and associated complexity while maintaining magnetic field compatibility
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 SMPS ensures high power delivery efficiency, reduces wiring complexity, eliminates heat management needs, and allows for placement of equipment closer to the MRI magnet, enhancing image quality and system scalability.
Implementation Method 1
switching frequencies such that electromagnetic interference generated via corresponding switching frequency harmonics is generated at frequencies appearing only outside the imaging bandwidth
Implementation Method 2
A switched mode power supply (SMPS) using air core magnetic energy storage components
Data Source
AI summary
A switched mode power supply (SMPS) employs only energy storage components that are devoid of ferromagnetic materials. The SMPS operates only at switching frequencies such that any potential electromagnetic interference of interest is generated at frequencies appearing only outside the imaging bandwidth of a corresponding magnetic resonance imaging system powered by the SMPS.