Electric drives and energy management for a diesel-electric ship propulsion system

Initial situation

Up until now the use of diesel-electric ship propulsion systems was not economically viable as they did not fulfil the requirements for weight and size. However, stricter emission regulations and a stronger environmental awareness make the use necessary. 

Task

Development of the electric drive technology for a diesel-electric ship propulsion system including power management. Furthermore, the aim is to reduce consumption and thus also emissions. 

Implementation 

The GMS ENOK, an inland waterway cargo vessel 85m in length and with a tonnage of 1 505 t was converted to a diesel-electric ship propulsion system. Four diesel generators with 230 kW permanent magnet generators each provide power for the four torque motors of the diesel-electric ship propulsion system. Two torque motors each are combined in a shafting string and directly drive the ship's propeller. 

ARADEX components control the generator and the torque motors. Seven VECTODRIVE® VD600 400A1 inverters supply electricity, created by the generators, to the DC link (with 650 V). The DC links serves the power users of the on-board system as well as the ship's drive. 

Two VECTONUM® controllers ensure the precise coordination between generators and torque motors – in all operating modes. The technology module "diesel-electric power management", specifically developed for this application, controls the sophisticated energy management of the diesel-electric propulsion system. The ARADEX power management compensates for abrupt changes in power in less than 1 ms – thereby preventing a surge voltage in the intermediate circuit. 

Results 

25% reduced consumption and ideal emissions due to the ideal efficiency factor and the modular drive concept. Improved shallow water characteristics as the generators can be installed anywhere and not necessarily next to the propulsion motors. Sensitive manoeuvring thanks to full torque starting right from the first rotation.

Case Study: Energiemanagement für einen diesel-elektrischen Schiffsantrieb

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