Three-phase three level, soft switched, phase shifted PWM DC-DC converter for high power applications

A new three-phase, three-level dc to dc phase shifted pulsewidth modulation (PWM) converter is proposed for high power and high input voltage applications. Output voltage Is controlled by incorporating phase shift PWM. Clocked gate signals of each leg are phase shifted by 2 pi/3 from each other. Major features of the converter include: 1) outer two switches of each leg are turned on and off as zero voltage switching, 2) inner two switches of each leg are turned on and off as zero current switching, and 3) this is achieved without involving any extra passive or active components. The secondary side of the converter is of center tapped full-wave current tripler type. This results in an increase of ripple frequency by a factor of six, leading to a significant reduction in size of the output filter. In order to obtain behavioral and performance characteristics of the proposed converter topology, detailed analytical and simulation studies are carried out. Finally the viability of the scheme is confirmed through detailed experimental studies on a laboratory prototype developed for the purpose.