Compact and Modular Power Units for Remotely Operated Vehicles

This paper presents an ISOP (Input-Series-Output-Parallel) modular architecture using interleaved isolated DC-DC power units with fault-tolerant capabilities to supply reliable power to subsea remotely operated vehicles (ROV s) at high system efficiency and power density. The proposed power converter units are constructed using a solid-state transformer (SST) for stepping down the medium voltage DC (MVDC) from the power umbilical to a lower voltage DC (LVDC) that can be used to power the ROV's thrusters, auxiliary loads, etc. A closed-loop control strategy of the output voltage and module current of the ROV's power unit with due consideration of “N-I” redundancy for fault tolerance of the system is proposed in this work. Interleaving of converter modules is also implemented to reduce the noise and hence the filter size. Real-time Hardware-in-the-Loop (HIL) results based on a Typhoon HIL system are presented to verify the converter's operation.