Electric Ship Propulsion with Induction Motor Drive and Li-Ion Battery based Back-up Capability

This paper deals with an IM propulsion drive for a ferry. The ship under test is moved by two twin propulsion units. Each IM drive is supplied by three-level neutral point clamped voltage source inverters in a back-to-back configuration. To increase the reliability of the IM drive in case of failure of one of the main generators on-board, a Li-ion battery pack is connected to the DC link of the drive by a DC-DC full-bridge bidirectional converter in order to provide the drive rated power for the time needed for a cold starting of the auxiliary generators on board. Results show the Li-ion battery pack is able not only to provide the power required by the drive, up to its rated value, but also to help the on-board healthy generators in supplying the loads in case of reduced power required by the propulsion drive.