Z-Source Converters: Topologies, Modulation Techniques, and Application–Part I

Power electronic converters have been intensely researched and developed over the last decades. New solutions and topologies have still been in high demand in order to increase the conversion system reliability and efficiency with decreased cost, volume, and weight. The impedance source converter (ZSC) was introduced first by Peng in 2002, aiming to overcome some of the limitations associated with traditional power electronics converters. The topology was three-phase, two -level voltage source inverter derived. The solution consisted of six power transistors, one diode, two inductors, and two capacitors. The introduced impedance circuit allowed for one -stage conversion with buck and boost capability and helped to eliminate the need for dead-time protection. The topology became a short-circuit tolerant solution, which helped improving the system reliability. The short circuit of the leg switches was named shoot-through, which was intentionally used for boosting the input voltage. Since then, tens of solution modifications, improvements, and applications have appeared. The solution was adopted to all existing types of power converters, i.e., dc-ac, dc-dc, ac-dc, and ac-ac. The topologies were used for various applications such as photovoltaic (PV) systems, wind energy conversion, fuel cells, uninterruptible power systems, motor drives, energy storage systems, and power factor correction. With every day and event, there are new solutions and applications based on the ZSCs.