High precision current tracking PWM amplifier with optimal type 1 digital controller for generating magnetic field in MRI systems

This paper presents a two-paralleled PWM amplifier using switch-mode power current tracking technique in order to generate a gradient magnetic field in a magnetic resonance imaging (MRI) system. This circuit has 8-IGBTs at their inputs/outputs so as to realize further high-power density. A digital control scheme can minimize the current ripple and improve its control response in the gradient coils. It is proved that the proposed technique will highly enlarge the diagnostic target and improve the image quality of MRI.