Transient analysis of a trans quasi-Z-source inverter working in discontinuous conduction mode

This paper presents a transient analysis of the trans quasi-Z-source inverter (trans-qZSI) topology operating in discontinuous conduction mode (DCM). Usually only the continuous conduction mode (CCM) is considered and high current operating points are assumed in the literature. Thus the main contributions of this article are a clear definition of the limits of the DCM and the development of a small-signal model that takes into account the dynamics introduced by the particular Z network contained in the trans-qZSI converter, which allows the behaviour of the system working in DCM to be analysed under different current demand circumstances. Moreover, the obtained small-signal model allows the expressions of the control-to-capacitor transfer function to be derived and used together with any inverter control strategy. For trans-qZSI topology performance analysis and model validation, computer simulation results are presented, including frequency domain analysis and small-signal/PSIM comparisons. Lastly, experimental validation is presented for the time and frequency domains.