Analysis of circuit path and current stress of power devices under shoot-through mode in Z-source inverter

The three shoot-through modes in Z-source inverter are one-phase, two-phase and three-phase shoot-through. The current stress of the power device is lowest in the third mode. Generally, in three-phase shoot-through mode, the current stress of power devices is analyzed based on big shoot through current, and its value is greater than the peak value of load current. This paper reveals the current stress of power devices is equal to the peak value of load current with small voltage gain and low power factor. Current path of the load in three-phase shoot-through mode is analyzed, which supports further analysis on loss, temperature increment and thermal management of the power devices. It is shown that freewheeling current path in shoot-through state is different if the value of shoot-through current is different. The expression of power device current stress is obtained under different freewheeling conditions, which provides the theoretical basis for the selection of the current level of power devices. Experimental results verify the theoretical analysis.