CAD simulation of drive converters on isolated marine power systems
Power electronic converters are being increasingly used on isolated marine power systems, to provide variable speed control of electric motors. As the rating of these drive converters increases, the converter load becomes a significant part of the total system load. Traditional methods for calculating the performance characristics, which assume the presence of an infinite busbar on the system, are not appropriate for such systems. The intercoupling which exists between system components such as synchronous generators, converters, and the drive motor must be included in the calculation. In this thesis, a commercially available software simulator Saber, is used to model a complete electrical cycloconverter propulsion drive, of the type which may be used for future Royal Navy frigates. This model includes the synchronous generators, cycloconverters, and induction motor drives. The simulation is performed in the time domain, which ensures that the intercoupling present between system components is preserved. The simulation is not restricted to one converter configuration, and has been used to investigate the relative merits of a number of possible converter connections. This method can be used to study drive performance under unbalanced conditions as well as for normal balanced operation. There is no perceived limit to the size, or complexity, of the converter systems which can be studied using this method. The only cost would be increased computer run times.