A Comparative study of a T-type Asymmetrical Multilevel Inverter with Two Different Sources with Conventional H-bridge Converter

Abstract

In this paper, a comparative study of a T-type Asymmetrical multilevel inverter (ASMLI) with two sources namely a Battery as a low voltage source and solar with boost converter as a higher voltage source is analyzed with respect to a conventional H Bridge Converter. Two switches with an antiparallel diode are used to modulate the low voltage level and a conventional VSI is used to obtain a high voltage level in the power circuit. A state space model is derived and stability analysis is performed. A vertical shifted SPWM control is used for obtaining switching mechanism of the ASMLI circuit. The analytical study ASMLI is interfaced between the low level input voltage sources solar and/or battery with the AC load or AC grid. It is observed that the system is well stable by taking the output voltage and inductor current. A comparison with a conventional H-Bridge inverter is brought about through various cases with single source. Total Harmonic Distortion, conduction losses, efficiency, voltage and current stresses are in detail compared and derived that this inverter is capable for applications for power ratings less than 100 KW. Also the stress and rate of change of current on the front end Boost converter is found to be approximately 50% less compared to a conventional based DC-AC configuration. The simulation is performed in PSCAD v4.6 and observation is done for 5 kW load with different power factor’s and also with different modulation indexes. For medium and low power applications, T-type Asymmetrical multilevel inverter (ASMLI) can be preferred.