The intention set for this book is to formulate a few topologies with enhanced voltage boost, while drawing continuous input current. To further reduce the device switching stress and improve the output waveform quality, a series of impedance-source NPC inverters based on transformer-capacitor impedance network inserted to the front-end of the NPC inverter bridge are proposed. These inverters integrate all advantages of the transformer-based impedance-source two-level inverters and classical NPC three-level switching. The proposed trans-Z-source NPC inverter has enhanced voltage boost capability over the traditional Z-source NPC inverters. The component selection process, voltage/current stress and efficiency comparison between the proposed inverters and traditional impedance-source inverters will all be covered in the book. Simulation and experimental results will also be given for verifying the theoretical analyses presented.