RF Power Supply Voltage Control for MRI Efficiency
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Solution Overview
Problem
The power efficiency of radio frequency power supplies in magnetic resonance imaging apparatuses decreases significantly when the output signal level is lower than the rated output level, leading to excessive drain voltage and increased heat generation.
Innovation Solution
A radio frequency power supply that dynamically varies the power supply voltage used by the amplifier based on the input signal magnitude, ensuring the drain voltage is not excessively high, thereby maintaining efficient power amplification across varying output levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the amplifier is adjusted for excellent power efficiency near rated output power, then power efficiency is improved at rated power, but power efficiency becomes low when output signal level is significantly lower than rated output level
Solution Approach 1:
The patent applies dynamics by making the power supply voltage variable rather than fixed. The controlling circuitry dynamically adjusts the power supply voltage to the amplifier based on the actual output signal level, allowing the system to adapt to varying operating conditions and maintain high power efficiency across different output levels, not just at rated power.
Solution Approach 2:
The patent changes the parameter of power supply voltage from a constant value to a variable value that depends on the output signal level. By modifying this electrical parameter dynamically, the system optimizes the operating point of the amplifier to maintain high power efficiency whether operating near rated power or at significantly lower output levels.
2Use of energy by moving object
If the amplifier operates in Class AB for excellent power efficiency near rated output, then power efficiency is improved, but electric power consumption increases and heat generation occurs when output signal level is significantly lower than rated output
Solution Approach 1:
The patent changes the power supply voltage parameter dynamically based on output signal level. When the output signal level is significantly lower than rated output, the controlling circuitry reduces the power supply voltage accordingly, which directly reduces electric power consumption and prevents excessive heat generation while maintaining adequate amplification performance.
Solution Approach 2:
The system employs feedback by having the controlling circuitry monitor the output signal level and adjust the power supply voltage in response. This closed-loop control ensures that the amplifier receives only the necessary power for the current operating condition, reducing energy waste and heat generation when operating below rated power.
Data Source
AI summary
A radio frequency power supply according to an embodiment is a radio frequency power supply that amplifies an input signal including application timing of a radio frequency magnetic field and waveform information and that supplies the amplified input signal to a radio frequency coil. The radio frequency power supply includes an amplifier and a controlling unit. The amplifier amplifies the input signal and to output an amplified signal. The controlling circuity varies power supply voltage used by the amplifier for the amplification of the input signal, in accordance with the input signal.