Tapped-inductor Z-source inverters with enhanced voltage boost inversion abilities

This paper presents the concept of using a new tapped-inductor (TL) Z-source impedance network for implementing Z-source inverters. By replacing the original two inductors found in the classical impedance network with two modified 2-terminal TL cells, output voltage range of the new inverter can widely be expanded. This means a larger gain, which in principle, can be adjusted freely by varying the turn ratio of the TL and the inverter shoot-through duration, which is now much shorter than that found in the classical Z-source inverter. Shorter shoot-through duration is in fact preferred, since it leads to a larger modulation index, and hence a better output waveform quality. Theoretical analysis for explaining these operating features has already been discussed throughout the paper, before simulation results are presented for verifying them. The proposed TL-network can also be applied to the quasi Z-source inverters with certain unique advantages achieved. For illustration, two example topologies are presented with their performance characteristics discussed.