Research the method of providing harmonicity to multi-level inverter

In this work we consider the developed scheme of multi-level invertor, which is collected on IGBT transistors. Transistor switching, which provides harmonicity of output tension, is calculated on each level. For verification the settlement data, the imitating model of multilevel inverter was constructed in MatLab program. The output curve tension received at the exit of multilevel inverter’s imitating model was spread out to harmonious components. It allowed investigating most precisely harmonious structure of the received multi-level inverter’s tension curve.
For ensuring output tension with a sinusoidal curve, researches and calculations of a corner of switching for each source of the multi-level inverter are conducted. Calculation of switching corner for each source for eight, twelve and twenty-six step single-phase inverters is carried out. For each step the necessary level of tension is provided, it carries out the harmonicity the whole inverter’s output tension. Calculations were carried out in algorithm presented below, in this case for eight, twelve, and twenty-six step inverters.
Multi-level inverter with an industrial frequency imitating model’s results showed that the most sinusoidal tension curve can be taken on high levels.
For the most detailed analysis we took spectral characteristics in Matlab modeling environment for eight, twelve and twenty six levels inverter, which reflects whole harmonic structure of tension curve. Analysis of harmonious structure for eight, twelve and twenty six-level inverters is also carried out.
Use of the multi-level inverter in transformation of solar energy to the electric power of an alternating voltage will provide from a constant source of solar elements a variable curve of tension of a sinusoidal form. Thus, multilevel creation of the inverter will allow saving quantity of expensive solar elements and excluding the filter that considerably increases mass properties of transformation systems. It can justify costs of the multi-level inverter of sinusoidal tension curve at the exit.

Author: Kyrmyzy Taissariyeva
Conference: Title