Grid Connected Single-Phase Multilevel Inverter

Abstract: In the microgid system, the distributed energy resource (DER) based inverters are usually adopted. Multilevel inverters have been attracting in favour of academia as well as industry in the recent decade for high power and medium voltage energy control and its multilevel concept is used to decrease the THD in the output waveform without decreasing the inverter power output and it also offer high power capability, lower commutation losses and less stress on semiconductor switches. The inverter topology in this paper is a five-level grid connected inverter having the ability to produce minimum THD with reduced number of switches and reduction in space utilization with simple control logic. The five-level inverter requires only six switches instead of eight required in the CCHB inverter. In addition, two active switches are operated at the line frequency. The most attractive feature of this proposed topology is that it requires only two carriers for developing the multilevel output; hence the control logic is simple. The inverter is simulated for both off-grid and on-grid applications. The inverter current THD is obtained as 1.74% which is less than 5.0% and compatible with the THD utility standards. Keywords: Distributed Energy Resources (DER); Photovoltaic (PV); DC/DC converter; Conventional Cascade H- Bridge Multilevel Inverter (CCHB).