Power conversion PWM amplifier with two paralleled four quadrant chopper for MRI gradient coil magnetic field current tracking implementation

This paper presents a two-paralleled PWM amplifier using switch-mode power current tracking technique in order to generate a gradient magnetic field in the 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 is adopted to minimize the current ripple and improve its control response in the gradient coils (GCs). It is proved that the proposed technique will highly enlarge the diagnostic target and improve the image quality of MRI.