Novel Cascaded Z‐Source Neutral Point Clamped Inverter

Abstract

Z-source Neutral point clamped (NPC) inverter inherits the advantages of Z-source inverter, which can buck-boost energy and allow the shoot-through states. At the same time, Z-source NPC inverter has high running efficiency and less harmonic content. Hence, it can be widely used in motor drives and fuel cell applications. When increasing the modulation index, one can only get smaller shoot through value in Z-source NPC inverter, therefore the output voltage of the inverter can not be boosted very high. In this paper, a novel cascaded Z-source neutral point clamped inverter is proposed by cascading two Z-source networks in series. An Alternative phase opposition disposition (APOD) carrier-based modulator is applied to control the proposed Z-source inverter. To confirm the operating principle of the new Z-source NPC inverter, a generic APOD carrier-based modulator for the cascaded Z-source NPC Inverter under Matlab/Sinmulink is built. The simulation results show that the boost factor has been increased from 1/(1 − 2D) for the traditional Z source NPC inverter to 1/(1 − 4D) for the proposed cascaded Z-source NPC inverter. A prototype of the cascaded Z-source NPC inverter has been set up. The experimental results verify that the new topology can increase the boost factor and expand the voltage regulation range of the inverter.