A New Modulation Technique for 15-level Asymmetric Inverter Operating with Minimum THD
Eduardo E. Espinosa, Alumno Tesista de Doctorado en Ingeniería Eléctrica, LCDA - DIE. Nos presentará aspectos relacionados con su tema de investigación, el día Viernes 13 de Diciembre de 2013 a partir de las 16:00 horas.
'A New Modulation Technique for 15-level Asymmetric Inverter Operating with Minimum THD' Eduardo E. Espinosa N.
Multilevel inverters are the alternative for medium voltage applications. Among the
inverters types there are symmetric and asymmetric topologies. The asymmetric
inverters have different DC voltage values. The most common topology is when the
different cells are implemented in cascade arrangement, where the DC voltage are in
multiples of 3, obtaining an AC voltage with 3n = 27 levels (n = 3 cascaded inverters).
This topology provides a load voltage with low harmonic content, THD < 3%. However,
this high quality voltage has a non-negligible drawback, which is the presence of
regeneration in some of the inverters, independent of load type. This phenomenon is
due to the modulation technique (Nearest Level Modulation) used by this inverter. In
this work, the asymmetric 15 level inverter is presented. This inverter is designed to
avoid the regeneration problem - power flow from the load to the inverter - in some of
the power cells. This is achieved by obtaining the firing angles associated with the
power cells considering a minimum load voltage THD. Finally, a power flow analysis is
accomplished and simulated results show the feasibility of this approach.
|Asymmetric Inverter with 15-levels. |