Implementation and Critical Investigation on Modulation Schemes of Three Phase Impedance Source Inverter

New control circuits and algorithms are frequently proposed to control the impedance (Z) source inverter in efficient way with added benefits. As a result, several modified control techniques have been proposed in recent years. Although these techniques are clearly superior to the simple boost control method which was initially proposed along with the Z-source inverter (ZSI), little or conflicting data is available about their merits relating to each other. In this paper, it is shown how the shoot-through periods are inserted in the switching waveforms of the power switches and the performances of them are analyzed based on the operation of ZSI. Simple boost control, maximum boost control, constant boost control and space vector modulation based control methods given in the literature has been illustrated with their control characteristics. A critical investigation on ripples of the impedance source elements, output voltage controllability, output harmonic profile, transient response of the voltage across the impedance source capacitor and voltage stress ratio etc has been presented with the simulation results. The simulation results are experimentally verified in the laboratory with digital signal processors (DSP). DSP coding for the above all control techniques has been generated by interfacing Matlab/Simulink with DSP C6000 tool box and signal processing block set.