Research On Single-phase Three-level Inverter With Impedence Networks

Multilevel converters have drawn tremendous interest in large power converte fielddue to their significant advantages regarding output power grade, harmonics quality, andpower factor, etc. Although the multilevel inverter has the advantage, most of them stillbelong to the buck converter. By means of introducing impedence network to thesingle-phase three-level inverter, this paper proposes a single-phase three-level inverterwith impedence network. It not only maintains the desired boosted ac output voltage, butalso improves the reliability and reduces the cost of the system through the introduction ofdirect volume.This paper first analyzes the single-phase three-level inverter with single Z-sourcenetwork, including the basic structure, working principle, boosting/reducing the voltagecharacteristic and the balance of neutral-point voltage. Based on consulting patentliterature, the space vector modulation of single-phase multilevel inverter is adopted. Byinserting the shoot-through vectors into the equivalent zero vectors and selecting differentredundant vectors flexibly, the inverter not noly maintains the desired boosted ac outputvoltage but also realizes the balance of voltage. Conclusions are verified with simulation.Considering the shortage of boost capacity with single Z-source network, this paperadopts cascading Z-source network and proposes the single-phase three-level inverter withcascading Z-source network. The topology can upgrade boost factor, and the result isverified with simulation.Finally, the propotype of the single-phase three-level inverter and single-phasethree-level inverter with single Z-source network is accomplished separately. AdoptingDSP and FPGA as the main control chips to complete the experimental verification. Theexperimental results verify the correctness of the theoretical analysis and simulation.