Five-Level NPC Based Grid-Tied Inverter with Voltage Boosting Capability and Elimnated Leakage Current

In this study, a new five-level common grounded grid-connected inverter is presented. In the proposed multilevel inverter, the charging and discharging process of the applied capacitors generate the output voltage waveform. Also, the proposed topology is based on neutral point clamped (NPC) topology. So, it can overcome the parasitic current issue in the photovoltaic (PV) system, which is the major problem in grid-tied PV applications. Additional significant features include-reduced filter size, lower total harmonic distortion (THD) of the injected current to the grid, and voltage boosting capability. The proposed grid-tied Inverter is based on Switched Capacitor (SC) cells in which the proposed structure is a five-level inverter which is capable of boosting the voltage with voltage gain of 1.5. Hence, in grid-tied applications, there is no need to an extra boost stage to make the output voltage peak value compatible with the highest amount of the grid voltage. The key point is that the boosting capability is obtained by a single input voltage source which makes the proposed structure compact and more efficient. Furthermore, the implemented capacitors are self-balanced and no control scheme is required to make a balance over their voltage. The feasibility of the proposed MLI has been simulated in MATLAB/Simulink environment.