Single Z-source based cascaded transformer multilevel inverter

This paper proposes a new topology of cascaded transformer based multilevel inverter using single Z-source. The suggested circuit consists of only one Z network and single DC voltage source, as a result installation area is reduced. In this topology the output voltage amplitude is not limited to DC voltage source and transformers turns ratios similar to traditional cascaded transformer based multilevel inverter and can be increased with Z network shoot-through state control. Besides, it is more reliable against short circuit. In this paper, by using particular switching algorithm, the modulation index of inverter is kept constant and output voltage is controlled by a shoot-through duty ratio, therefore Total Harmonic Distortion (THD) of output voltage is nearly constant for different boost ratio. The performance of suggested inverter and switching algorithm are validated with simulation results using MATLAB/SIMULINK software.