A New Seven-Level Modified Full Bridge Inverter With Reduced Number of the Switches for PV Applications

Multilevel inverters have great applications in medium-voltage and high-power applications and also have found successful industrial applications. Modified full bridge inverter is one of the most popular topologies among themultilevel inverters because of lower number of switches and simpler structure than others. In this paper, a seven-switch and seven-level modified full bridge topology is proposed. Compared to the practical seven-level inverters like neutral point inverters, the proposed inverter reduces three active switches and has lower conduction loss and simple control. The input voltage to the giveninverter is a DC source (Vdc) which has been shared betweenthree identical capacitors and it is capable of producing output of seven level (Vdc, 2Vdc/3, Vdc/3, 0, -Vdc, -Vdc/3, -2Vdc/3). As more steps are added to waveform, the harmonic distortion of theoutput waveform decreases. The proposed modulation enables the proposed inverter to operate under both active and reactive power conditions. A 1KVA single-phase sample circuit issimulated by the PSPICE software to verify the validity of the proposed topology and modulation method. The results show the proposed topology is suitable for photovoltaic (PV) applications.

Keywords:

Multilevel inverters , Modified full bridge , PWM modulation , Reactive power , PSPICE , grid-connected