Power Loss in Z-Source Inverters: A Comparative Analysis and a New Modulation Strategy for Efficiency Improvement

Z-source inverters (ZSIs) are notable for single-stage voltage boost capability while providing inherent shoot-through immunity. However, they suffer from significant power losses, primarily due to the shoot-through mode, which introduces higher switching and conduction losses. Additionally, ZSIs require more passive components compared to traditional two-stage inverters, leading to increased system size and cost. To address these challenges, Switched Z-source inverters (Switched ZSIs) have been developed. Switched ZSIs reduce component count and improve efficiency by incorporating an additional switch, which lowers the shoot-through duty cycle and mitigates conduction losses. A comparative study of power loss across three inverter topologies shows that Switched ZSIs effectively bridge the gap between traditional two-stage and ZSIs. However, despite these improvements, Switched ZSIs still experience significant switching losses in the shoot-through state, limiting their efficiencies and hindering the potential to reduce passive component size by increasing switching frequency. To overcome this, a novel modulation method is proposed that provides the capability to achieve smaller passive component sizes without a significant increase in switching losses. Simulation results validate the effectiveness of the proposed method, demonstrating improved efficiency and greater feasibility for ZSI-based power conversion systems.