A wavelet modulation method for a quasi-Z-source inverter

Abstract

A wavelet modulation strategy applied to a quasi-Z-source inverter was proposed. The regulating range of the shootthrough duty ratio could be increased by changing the locations of the sampling points set using traditional wavelet-modulation. The proposed modulation strategy divided the shoot-through zero vector into two portions, which were then individually inserted into both ends of the sampling time. Under the proposed strategy, the quasi-Z-source inverter could obtain a theoretical maximum constant shoot-through duty ratio without any extra switching frequencies. In addition, the proposed strategy was compared with traditional modulation strategies used in quasi-Z-source inverters. The boosting capacity, efficiency, harmonic and modulation ratio of the different modulation strategies for quasi-Z-source inverter were analyzed thoroughly. Finally, the performance of the proposed method was verified by simulation. Both the simulation results and theory verify that the strategy can reduce harmonic, increase voltage utilization rate, and enhance the boosting capacity.

Keywords

• quasi-z-source inverter
• wavelet modulation
• total harmonic distortion
• voltage utilization rate