Power supply with independently regulated multiple outputs

This paper presents a new power supply with independently-regulated multiple isolated-outputs, based on a phase-shift PWM control of a multi-leg bridge. The power supply was developed for a multi-level switched-gradient-amplifier for Magnetic Resonance Imaging (MRI) systems that require good regulation during all operating conditions for good image quality. The gradient driver is a challenging load, almost purely reactive with large power transients. The power supply topology consists on one half-bridge leg for each independent output plus an additional common leg. The control is achieved by phase-shifting each leg with respect to the common leg, with two transformers with their primary connected between its corresponding leg and the common leg. Experimental results obtained with a 60 kW prototype confirm the validity of the concept.