Estratégias de modulação PWM e controle aplicadas ao conversor multinível modular

Abstract

This thesis proposes two modulation techniques for the Modular Multilevel Converter (MMC). Where the modulating signals are compared to a carrier, generating the signals for the power switches. In this strategy the modulating signals receive the signals required to stability the capacitor voltage balance and control the internal currents of the sub-arms. As a strategy for controlling the internal current a controller was developed by hysteresis, keeping its value close to a reference value. The strategy of controlling the voltages in the capacitors is made from an algorithm in which the voltages of the capacitors are ordered in ascending order, after defining the voltage offsets to be applied in order to charge the capacitors lower voltage and discharge those with higher voltage. The second proposed strategy was based on the phase-shift modulation (PS) for the MMC converter whose sub-module is formed by the converter with flying capacitor. Strategies have been developed to control the internal current of the converter through an integral proportional controller and also a resonant proportional integral that attenuates the harmonic components of 2 and 4 order present in the internal currents. Strategies have also been developed to control the voltages in the internal and external capacitors of the submodules.