Three-phase Embedded Modified-Z-Source Three-Level T-Type Inverters

Abstract

Two topologies are designed by combining a modified-Z-source impedance (MZS) network consisting of three diodes, two inductors and four capacitors to the traditional three-level T-type inverter (3LTI), and embedding either one or two dc sources in the impedance network, which are named as asymmetrical embedded MZS-3LTI (AEMZS-3LTI) and symmetrical embedded MZS-3LTI (SEMZS-3LTI). The proposed topologies provide a highly boosted ac output voltage with five voltage levels and ensure a continuous dc source current by adopting the embedded concept. In comparison to other topologies combining the impedance network and 3LTI, the proposed SEMZS-3LTI topology has two times higher boost factor and the lowest ratio of voltage stress across capacitors to the ac output voltage. The modulation technique is proposed for effectively controlling the upper and lower shoot-through states with a simple logic circuit and balancing two series capacitor voltages. The validity of the proposed topologies and the modulation technique is demonstrated through simulation and experimental results.