Evaluation of a Dual MLC2 Converter for Electrified Ship Propulsion Application

In this work, a performance analysis on the application of the modular five-level multilevel clamped multilevel converter (5L-MLC2) for driving high-power machine, commonly used in naval plants for propulsion, is presented. Focus is on the topology using dual multilevel converters connected to induction motors with open terminals (open-end windings), that is, each end of the windings is connected to an inverter. The viability of this configuration is verified in this work. A comparison analysis is performed between the modular five-level multilevel clamped multilevel converter (5L-MLC2), and the well-known three-level neutral-point-clamped converter (3L-NPC). The strategy of applying phase shifted modulating signals between the converters, either with S-PWM or SVM, have been considered. Performance analysis with Matlab/Simulink was carried out with emphasis on FFT analysis and current and voltage levels on the semiconductor devices. Some results have shown reduced total harmonic distortion (THD%) at 120° phase shift with SVM. The proposed dual 5L-MLC2 based drive system has yielded significant reduction in total rated voltage of clamping diodes.