Switched-tapped-inductor Z-source inverters

This paper presents the concept of switched-tapped-inductor (STL) Z-source impedance network for implementing novel Z-source inverters with stronger voltage boost inversion ability. By replacing the common inductors of the classical Z-source impedance network by two improved 2-terminal STL cells that are derived from SL and TL cells, the output voltage range of Z-source inverters can be further expanded. Compared with the classical Z-source inverter, along with SL/TL Z-source inverters, the proposed topology increases the voltage boost inversion ability significantly, and only a very short shoot-through zero state is required to obtain high voltage conversion ratios. A detailed theoretical analysis is given under steady-state and the analytical results are validated by the simulation examples using simple boost control and the maximum boost control method, respectively. The proposed STL concept can also be extended to the topologies of quasi Z-source inverters. Two extended configurations, quasi TL Z-source inverters are presented for reference, which can further improve the circuit characteristics.