A new high power transformer-less voltage source converter proven on a marine electric propulsion

This paper deals with a transformer-less Variable Speed Drive based on High Power Medium Voltage PWM Voltage Source Converters connected to a distribution network without transformer. This technology represents the new generation of high efficient and compact power conversion solution. The transformer-less “architecture” of this variable speed drive was proposed thanks to a global system study combining several domains (power electronic, control, magnetic component design & circuit topology) and was applied to the diffential mode circuit study as well as the common mode circuit study. We detail the main key-point of the transformer-less solution, but above all, thanks to a complete qualification campaign on a real propulsion system, we improve our theoretical models and our assumptions to the measurements in order to validate our transformer-less solution. We describe the main concordances and explain the differences.