Auto-tuning of the RF transmission line coil for high-fields magnetic resonance imaging (MRI) systems

Sohn, Sung-Min; Vaughan, J. Thomas; Gopinath, A.

doi:10.1109/mwsym.2011.5972842

Cited by 4 publications

(4 citation statements)

References 5 publications

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“…where the last step is obtained by plugging in equation (1). The conduction loss in the PSIM switch P cond can now be computed as i 2 sw,rms R DS,ON , where R DS,ON is the dynamic on-state resistance of the switch [26]- [28].…”

Section: Loss Characteristics Of a Psim Element A The Basic Psim Capa...mentioning

confidence: 99%

“…A wide range of existing and emerging applications require the delivery of radio-frequency (rf) power into widely-varying loads at power levels up to several kilowatts and beyond. Examples include magnetic resonance imaging [1], [2], wireless communications [3], wireless power transfer [4]- [8], and plasma generation [9], [10]. The wide variation in load impedance in many of these applications makes it challenging to achieve efficient rf power generation while maintaining acceptable loading of the rf amplifier or inverter, and providing accurate control of power delivered to the load.…”

Section: Introductionmentioning

confidence: 99%

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A 1.5 kW Radio-Frequency Tunable Matching Network Based on Phase-Switched Impedance Modulation

Bastami

Jurkov

Nguyen

et al. 2020

IEEE Open J. Power Electron.

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Dynamically-tunable impedance matching is a key feature in numerous radio-frequency (RF) applications at high frequencies (10 s of MHz) and power levels (100s-1000 s of Watts and above). This work develops techniques that enable the design of high power tunable matching networks (TMN) that can be tuned orders of magnitude faster than with conventional tunable impedance matching techniques, while realizing the high power levels required for many industrial applications. This is achieved by leveraging an emerging technique -known as phase-switched impedance modulation (PSIM), which involves switching passive elements at the rf operating frequency -that has previously been demonstrated at rf frequencies at up to a few hundred Watts. In this paper, we develop design approaches that enable it to be practically used at up to many kilowatts of power at frequencies in the 10 s of MHz. A detailed analysis of the factors affecting the losses as well as the tradeoffs of a basic PSIM-based element is provided. Furthermore, it is shown how incorporating additional stages to the PSIM-based element, including impedance scaling and / or the addition of series or shunt passive elements, influences the losses and enables the efficient processing of high power levels given the limitations of available switches. A PSIM-based TMN that matches load impedances to 50 and delivers up to 1.5 kW of power at frequencies centered around 13.56 MHz is implemented and tested over a load impedance range suitable for various industrial plasma processes.

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Section: Loss Characteristics Of a Psim Element A The Basic Psim Capa...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A 1.5 kW Radio-Frequency Tunable Matching Network Based on Phase-Switched Impedance Modulation

Bastami

Jurkov

Nguyen

et al. 2020

IEEE Open J. Power Electron.

View full text Add to dashboard Cite

show abstract

“…As shown in the matching block of the MRI (see Figure 1), RF passive components are implanted on coils, including adjustable capacitors. As a variable capacitor, a trimmer can tune the frequency (the tuning capacitor C t in Figure 1b), by setting a precise capacitance value [6,7]. Furthermore, low capacitance values (a few pF) are commonly used for matching impedance (the matching capacitor C m in Figure 1b) [6].…”

Section: Introductionmentioning

confidence: 99%

“…As a variable capacitor, a trimmer can tune the frequency (the tuning capacitor C t in Figure 1b), by setting a precise capacitance value [6,7]. Furthermore, low capacitance values (a few pF) are commonly used for matching impedance (the matching capacitor C m in Figure 1b) [6].…”

Section: Introductionmentioning

confidence: 99%

FEM simulation‐based development of a new tunable non‐magnetic RF high voltage capacitor for the new generation of MRI

Jebri

Bord‐Majek

Bardet

et al. 2022

The Journal of Engineering

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Using Radio Frequency (RF) waves, magnetic resonance imaging (MRI) systems can make detailed images of human organs for accurate diagnostic processes and disease detection. The overhaul of certain electronic components has become necessary to keep up with the progress of MRI systems. Among the components responsible for image quality, the adjustable non-magnetic capacitors, also called trimmers, are of great importance. The purpose of this paper is to suggest a new design of a trimmer using non-magnetic materials, able to hold a high voltage ( >3 kV) and reach a resonance frequency above 100 MHz. Constructional analysis performed on existing commercial trimmers, combined with the electrical Finite Element Method, were carried out to propose a prototype matching the desired specifications. A dielectric shield surrounding the electrodes was sized to ensure voltage withstand. Moreover, the rotor and the worm-and-gear set were joined together to combat the vibrations generated by the MRI system. The present study includes the modelling step of the component by numerical simulation, the manufacturing, the electrical performance characterization, and the mechanical solution for tuning capacitance. The final prototype combines electrical performance corresponding to the required specifications in particular a high breakdown voltage (39.7 kV) and a resonance frequency (130 MHz).

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Frequency-tuning Matching Network for Load-varying Applications

Ye,

Surakitbovorn,

Lin

et al. 2024

2024 IEEE Applied Power Electronics Conference and Exposition (APEC)

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Auto-tuning of the RF transmission line coil for high-fields magnetic resonance imaging (MRI) systems

Cited by 4 publications

References 5 publications

A 1.5 kW Radio-Frequency Tunable Matching Network Based on Phase-Switched Impedance Modulation

A 1.5 kW Radio-Frequency Tunable Matching Network Based on Phase-Switched Impedance Modulation

FEM simulation‐based development of a new tunable non‐magnetic RF high voltage capacitor for the new generation of MRI

Frequency-tuning Matching Network for Load-varying Applications

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