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Three-phase Quasi Z-Source Inverter (QZSI) provides a promising solution for single-stage transformerless grid-connected photovoltaic (PV) systems. In recent years, many PWM techniques with different shoot-through (ST) mechanism are proposed to improve the performance of the QZSI. However, these techniques generate a high common-mode voltage (CMV), which produces a leakage current flow through the parasitic capacitances between the PV panel and the grid. Due to the lack of galvanic isolation in transformerless PV systems, the leakage current becomes an even more pronounced problem. This current may lead to critical safety issues and other effects on the PV system. This paper introduces an analytical study of most of the presented PWM techniques for QZSI including three-leg ST and single-leg ST schemes in terms of the CMV characteristics. Consequently, a comparison that includes the CMV …