The following thesis was performed on behalf of METS Technology, which is a company that worsk with electrification of vehicles in the marin and offshore sectors. The company gave the task of simulating short circuit current and selectivity in one of their drive systems. The circuit is a hybrid system that is will be examined when the batteries are disconnected. The problem arises when the system uses compact converters with limited conductance, which imitates the abuility to generate current spikes during any faults or short circuits. METS have as a temporary solution to use external capacitors but wants to investigate if there are other solutions to the same problem in other branches. If there’s no other suitable solution, the external capacitor should be dimensioned and modelled together with the rest of the circuit and simulate different short circuit scenarios.

The work began with literature studies, which concluded that the capacitor was the most attractive solution for METS. This was followed by modelling the system where the first step was to understand MATLAB and how short circuits function within circuits. The initial modules showed that the short circuits current coming from the capacitors largely depends on the charged voltage and the resistance to the short circuit. This then provided a solid foundation for the final model.

Datasheets and information from METS, made it possible to model a stable system capable of handling short circuits. With the completed model, it was possible to simulate different types of short circuits. The result of the simulations showed that the system required six external capacitors with a total capacitance of 15 mF to blow all fuses.