抄録
This paper presents a Multiple Bridges Power Conversion Circuit (MBPCC) for the switchmode gradient power amplifiers in the magnetic resonance imaging (MRI) systems. The MBPCC is connected in parallel with the conventional 4-switch full-bridge circuits using insulated gate bipolar transistors (IGBTs) at their inputs/outputs in order to realize further high-power density. A unique digital control scheme for MBPCC, which requires minimized the ripple and improved the rise/fall response characteristics of the current in the gradient coil, is proposed and described here. The MBPCC as overall system is perfectly suited to the gradient power amplifier for advanced MRI because the output current waves are not restricted to ramped-squarewaves and can assume any arbitrary forms. It is expected that the proposed techniques will highly enlarge the diagnostic target and improve the image quality of MRI.
