Experimentally verification of the characteristic of a single-phase line-to-line 7-level inverter under loaded condition

Abstract

This paper validates the characteristics of the single-phase line-to-line 7-level inverter under loaded condition (890W). The feature of this inverter is that the circuit is the same as a conventional A-NPC type 3-level inverter, but the DC voltage sources are asymmetry. The voltage value of one DC voltage source is set twice as large as that of the other. Simulation results show that the voltage THD of the proposed 7-level inverter can be less than those of the conventional 2-level inverter, the A-NPC 3-level inverter. Experimental results of the proposed 7-level inverter, where a dead time and its compensation are implemented, are mostly in agreement with the simulation results. Furthermore, when the output voltage reference is large, the proposed 7-level inverter can reduce the current THD and the amount of electric charges supplied from each cell battery in the voltage sources can be almost equalized.