This Master Thesis presents the design, control and testing of a Modular Multilevel Converter (MMC) prototype. This Voltage Source Converter (VSC) topology provides several advantages compared to previous generations for High-Voltage Direct Current (HVDC) applications, such as reduced harmonic distortion and lower switching losses. Today, most of the planned VSC-HVDC projects are based on the MMC technology. First, a mathematical model of the MMCs is obtained. Based on the analytical description of the converter, two di erent control strategies for MMCs are studied and its performance is evaluated by means of time domain simulations developed in Matlab Simulinkr. The second part describes the construction of a 5 kVA MMC prototype, focusing on the converter submodule design. A procedure to de ne its main circuits, including the components' selection, is detailed. Then, the layout of the submodule PCB is designed using Altium Designerr. Finally, an experimental MMC prototype is built based on the developed hardware design. Then, the studied control strategies are implemented in order to analyze their performance in a real setup. The control and modulation of the MMC is programmed in a Digital Signal Processor (DSP). The obtained experimental results show an adequate behavior of the prototype for the implemented controllers. Carlos Collados