Harmonic optimization for multilevel converters using space vector fundamental frequency modulation

Multilevel converters feature a staircase output voltage, resulting in a lower number of switching operations and better spectral characteristics. Switching every element only once a load cycle (fundamental frequency switching), losses can be minimized. By calculating optimum switching angles, the emergence of lower harmonics can be avoided. Derived from conventional space vector modulation (SVPWM), a novel method overcoming the complexity of selective harmonic elimination (SHE) is presented. It optimizes the spectrum while being suitable for real-time calculation. A simple and easy to implement routing algorithm to choose appropriate switching states is given, which works for an arbitrary number of levels. Finally, results from both space vector fundamental frequency modulation (SVFFM) and selective harmonic elimination are compared.