Simulation, Analysis and Experimentation of Cascaded Z-Source Multilevel Inverter for Photovoltaic Applications

In recent years, multilevel inverters are widely employed for distributed energy sources area because several batteries, fuel cell, solar cell and wind turbine can be connected through MultiLevel Inverters (MLI) to feed a load without voltage balance problems. But the main disadvantage of MLI is its output voltage amplitude is limited to DC sources voltage summation. To overcome this drawback, a novel cascaded multilevel Z-source inverter for PhotoVoltaic (PV) system is proposed in this paper. The proposed topology for PV system can achieve single energy conversion and boost function. The integrated Z-source network in each module is immune to shoot-through faults especially operating at high switching frequency and enhances the system reliability.Various modulation strategies have been reported in the literature for cascaded multilevel Z-Source inverter. This paper will focus on simple boost control, maximum boost control and maximum constant boost control.A comparative evaluation of control methods are presented in terms of Total Harmonic Distortion (THD), inductor current ripple of Z-Source inverter, capacitor voltage ripple of Z-Source inverter, voltage gain and voltage stress. Simulations of the circuit configuration of various control methods are performed in MATLAB/SIMULINK. Hardware prototype of the proposed three-phase cascaded multilevel Z-source inverter for PV is built to validate the results.