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

Abstract

Two topologies are designed by combining a modified-Z-source (MZS) network consisting of three diodes, two inductors and four capacitors to a 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. Operating analysis is performed and a comparison of the two proposed topologies with five different topologies combining the impedance network and 3LTI or neutral-point-clamped (NPC) inverter is provided. A novel modulation technique is proposed for effectively controlling the upper and lower shoot-through states with a simple logic circuit and balancing a neutral-point voltage. The validity of the proposed topologies and the modulation technique is demonstrated through simulation and experimental results.

Keywords

• Boost capability
• embedded dc source
• Z-source impedance network
• modulation technique
• three-level T-type inverter (3LTI)