A novel control method for Z-source inverters used in photovoltaic systems

In this study, a novel Space Vector Modulation based control method is proposed to improve steady state and transient performances of Z Source Inverter (ZSI) used in photovoltaic systems while limiting voltage stress across inverter switches. In the proposed method, it is possible to get a simple relation between impedance network capacitor voltage and inverter output voltage. Thus, ZSI output voltage can be controlled with only capacitor voltage feedback. Furthermore, control of modulation index is provided without an additional control loop by eliminating zero state, and thus it could be possible to work with an adjustable dc line voltage. Therefore, voltage stress across inverter switches is limited. Limited voltage stress provides higher efficiency by reducing switching losses, and it also helps reduce the cost by letting use low cost switches. The performance of the proposed ZSI control method is verified through Matlab/Simulink simulations.