Design Method of Digital Optimal Control Scheme and Multiple Paralleled Bridge Type Current Amplifier for Generating Gradient Magnetic Fields in MRI Systems

Shuji Watanabe, Hiroshi Takano, Hiroya Fukuda, Eiji Hiraki, Mutsuo Nakaoka

Research output: Contribution to journalArticle

1 Citation (Scopus)


This paper deals with a digital control scheme of multiple paralleled high frequency switching current amplifier with four-quadrant chopper for generating gradient magnetic fields in MRI (Magnetic Resonance Imaging) systems. In ordcr to track high precise current pattern in Gradient Coils (GC), the proposal current amplifier cancels the switching current ripples in GC with each other and designed optimum switching gate pulse patterns without influences of the large filter current ripple amplitude. The optimal control implementation and the linear control theory in GC current amplifiers have affinity to each other with excellent characteristics. The digital control system can be realized easily through the digital control implementation, DSPs or microprocessors. Multiple-parallel operational microprocessors realize two or higher paralleled GC current pattern tracking amplifier with optimal control design and excellent results are given for improving the image quality of MRI systems.

Original languageEnglish
Pages (from-to)894-902
Number of pages9
JournalIEEJ Transactions on Industry Applications
Issue number8
Publication statusPublished - Sep 1 2003
Externally publishedYes



  • digital optimal control
  • dual-loop current feedback
  • gradient magnetic field
  • multi-parallel bridge type current amplifier

ASJC Scopus subject areas

  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering

Cite this