RF Amplifier Supply Switching for Multi-Mode MRI Power Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current RF amplifiers in MRI systems are optimized for a single operation mode, making it inefficient to switch between different peak power requirements, especially in applications like amide proton transfer (APT) sequences where rapid mode switching is necessary, due to limitations in capacitor bank capacitance and DC power supply reaction time.
Innovation Solution
Integrating multiple power supply devices with different voltages and using a fast solid-state switch to adapt the drain voltage of the RF amplifier, allowing efficient operation at both high and low peak powers by compensating voltage drops with a capacitor bank and managing parameters via a controller based on RF sequence demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single operation mode is used to optimize amplifier performance, then efficiency is improved for that specific mode, but the amplifier cannot efficiently handle other power requirements
Solution Approach 1:
The patent implements dynamic switching between multiple power supply voltages (e.g., 50V for high power mode, 25V for low power mode) based on real-time operational demands. This allows the amplifier to adapt its drain voltage to match the required power level, maintaining high efficiency across different operation modes rather than being locked into a single optimized state
Solution Approach 2:
The system changes the electrical parameter (drain voltage) of the amplifier by switching between different power supply voltages. This parameter change enables the amplifier to operate efficiently at different power levels - using higher voltage for high power modes and lower voltage for low power modes, thus resolving the contradiction between single-mode optimization and multi-mode versatility
2Loss of energy
If DC power supply voltage is changed to optimize efficiency for different power levels, then power efficiency is improved, but switching time becomes too slow for rapid mode changes
Solution Approach 1:
Multiple power supply devices are pre-configured with different voltage levels (e.g., 50V and 25V) before operation begins. When mode switching is required, the system simply selects from these pre-prepared voltage sources rather than generating the voltage change in real-time, enabling rapid switching while maintaining efficiency optimization
Solution Approach 2:
The patent introduces switching devices (such as solid-state switches or RF switches) as intermediaries between the multiple power supply devices and the amplifier. These switches enable rapid voltage selection by providing a fast switching mechanism that decouples the slow voltage generation process from the fast switching requirement, allowing mode changes within milliseconds
3Duration of action of moving object
If high power is delivered for extended periods, then continuous application requirements are met, but voltage drop becomes too large to maintain desired RF pulse envelope
Solution Approach 1:
Capacitor banks are pre-charged to the appropriate voltage levels before high-power RF pulses are generated. This preliminary energy storage ensures that when the pulse is generated, the full voltage is available immediately, preventing voltage drop during the pulse duration and maintaining the desired RF pulse envelope precision
Solution Approach 2:
The capacitor banks act as energy buffers that compensate for voltage drops during high-power operation. By storing energy in advance, they provide a cushion that maintains stable voltage delivery during extended continuous operation, ensuring the RF pulse envelope remains precise even under heavy load conditions
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 rapid and efficient switching between operation modes, achieving high power efficiency and supporting diverse MRI applications by optimizing voltage settings in real-time, even during short-time high-power demands.
Implementation Method 1
the at least one capacitor bank is connected to a conductor path between the power supply device and the RF amplifier. In order to compensate a voltage drop at the time of the operation of the amplifier, the capacitor bank supplies power to the amplifier as needed.
Implementation Method 2
using a fast solid-state switch to adapt the drain voltage of the RF amplifier
Data Source
Figure 1
Figure 2
AI summary
The present invention is directed to a RF transmit system (1) for a magnetic resonance examination system where it is intended to provide a solution for the problem of rapidly switching between operation modes of different peak power requirements at good power efficiencies. For this purpose the RF transmit system (1) comprises at least one RF channel (14) wherein the RF channel (14) has an RF amplifier (3), at least two power supply devices (4, 5) wherein each of the power supply devices (4, 5) is configured to supply a voltage to the amplifier (3). The RF transmit system (1) further comprises a DC switch (8) configured to switch the voltage supplied to the amplifier (3) between the power supply devices (4, 5) and a controller (2) configured to switch the voltage based on sensor data.