Analysis of freewheeling state in Z-source inverter under three-phase shoot-through mode

The Z-source Inverter (ZSI) is an attractive topology for the power electronics interface. In ZSI, there are three shoot-through modes: one phase, two phases and three phases shoot-through mode. Current stress of power device in the third mode is the lowest. The freewheeling state of ZSI under three-phase shoot-through mode was analyzed after deriving the expression of power device current stress. It was shown that the freewheeling current path will be different with different shoot-through current. The expression of power device current stress is obtained under different freewheeling condition. The current attenuation function of the traditional voltage source inverter (VSI) and ZSI in traditional zero state was obtained, in which the different effects on the current distortion are shown. Compared with VSI, ZSI is in favor of improving output current waveform quality. These theoretical findings have been verified using both simulations and experimental results.