Two-Paralleled PWM Power Amplifiers to Generate Highly Precise Gradient Magnetic Fields in MRI Systems

다국어 초록 (Multilingual Abstract)

This paper presents a two-paralleled 4 quadrant DC chopper type PWM power conversion circuit in order to generate a gradient magnetic field in the Magnetic Resonance Imaging (MRI) system. This power amplifier is connected in parallel with the conventional 4-quadrant DC chopper using IGBTs at their inputs/outputs to realize further high-power density, high speed current tracking control, and to get a low switching ripple amplitude in a controlled current in the Gradient Coils (GCs). Moreover, the power conversion circuit has to realize quick rise/fall response characteristics in proportion to various target currents in GCs.<br/>
It is proposed in this paper that a unique control scheme can achieve the above objective DSP-based control systems realize a high control facility and accuracy. It is proved that the new control system will greatly enlarge the diagnostic target and improve the image quality or MRf.

목차 (Table of Contents)

• ABSTRACT
  
• 1.INTRODUCTION
  
• 2.OPTIMAL PULSE LAYOUT FOR IGBT GATE SIGNAL IN PROPOSED CIRCUIT
  
• 3.THE DESIGN OF OPTIMAL TYPEL DIGITAL CONTROL SYSTEM
  
• 4.SIMULATION RESULTS
  
• 5.CONCLUSIONS
  
• 6.REFERENCES