Novel continous space vector modulation in cascaded multilevel converters

DC to AC conversion technology has succeeded in obtaining high power quality (voltages and currents) using multilevel inverters. These inverters can generate several levels of voltage that reduce the harmonic distortion of the generated sine waves in the AC side. However, the output voltages always are discrete, so a non-negligible harmonic distortion remains. This distortion can be reduced by increasing the number of voltage levels generated by the multilevel inverter, but this means reduce the reliability and increase the number of semiconductors. This paper proposes a novel continuous space vector modulation (C-SVM) that generates continuous AC voltages without using filters and reduces the total harmonic distortion (THD) of the voltage under 1%. This proposed modulation requires two variable power sources (e.g. buck converters) but can be implemented in simplified three-phase cascaded multilevel converters. Moreover, this continuous modulation allows the implementation of a novel cascaded multilevel inverter with a reduced topology. Simulated results show the proposed space vector modulation and the output voltage and currents obtained in inductive loads and in an induction motor.