Analysis of Cascaded Z-Source Topology Implementing DC-Link Voltage Balancing

Abstract

Cascaded Z-Source topology coupled with a three-level diode clamped inverter provides an alternative multilevel buck-boost power conversion. Z-Source Inverter utilizes the shoot through states to conjoin the diode clamped inverter with one of the sources in the cascaded Z-Source topology. This unique integration during the shoot through states of the inverter facilitates the boosting of the three-level output voltage. In this paper, de-link voltage balancing of the cascaded topology when the input sources are non-identical is proposed. Reference disposition modulation method is utilized to couple the inverter to the Z-Source topology. The mathematical modelling of the cascaded impedance networks for the non-identical condition is derived in this paper. The circuit analysis proves that the de-link voltage balancing is attainable by carefully adjusting the duty cycle of the shoot through states. Subsequently, simulations results carried out in MATLAB/Simulink platforms validate the mathematical modelling of the cascaded Z-Source topology.