A novel modulation technique with interleaved‐and‐shifted shoot‐through state placement for quasi‐Z‐source inverters

Summary In this paper, a single‐phase quasi‐Z‐source (qZS) inverter (qZSI), integrating the pulse width modulation (PWM) control with interleaved‐and‐shifted shoot‐through state (STS) placement modulation technique, is proposed to simultaneously achieve both dc voltage boost and dc‐ac inversion. Instead of placing the STS in both inverter legs simultaneously, the addressed method inserts the STS only in left/right inverter leg separately during the positive/negative half cycle of the output voltage to reduce switching losses and thermal stresses of the power devices. The STS shift is also studied to decrease the switching numbers of power devices and thus can improve the efficiency further. Theoretical analysis and design guidelines of the studied inverter are included. Improvement in effectiveness and performance of the devised scheme and modulation strategy are proved experimentally and compared with the previous studies on a built laboratory prototype. The proposed modulation strategy holds the minimum total switching numbers. Through the firmware programming in MCU, the gating signals of the switches on top side and bottom side can be evenly exchanged to turn on or turn off during the positive and negative half cycles. Accordingly, the switching losses can be significantly improved, and switches on both bridge legs have less thermal stresses as well as more balanced temperature rise.