Advantages of common DC busses on ships

Nowadays there is an increasing use of power electronic converters on ships. With power electronic converters motors can be controlled very accurately saving a lot of energy. However, the use of converters can lead to problems with harmonic distortion on the AC bus if for the rectifiers Diode Front Ends (DFE´s) are used. There will be no harmonic distortion when Active Front Ends (AFE´s) are used. However, Active Front Ends come at a high cost. But why should we use AFE´s on every converter? Why shouldn´t we use a common DC bus for all the power electronic converters? Only one AFE is needed (for redundancy reasons two). Advantages are fewer problems with harmonic distortion on the AC bus. Only half of the power electronic equipment is needed. Alewijnse has experience with this kind of DC bus on the sailing yacht Ethereal, completed in spring 2009. Use of a common DC bus where the high power consumers are connected, in combination with a small AC bus, seems to be the future of ships electrical systems. The layout of the system will be described, advantages and disadvantages of common DC busses and AC busses will be described, and the way how to make an AC bus from a DC bus will be described.