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 the steady-state and transient performances of the Z-source inverters (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, the ZSI output voltage can be controlled with only capacitor voltage feedback. Furthermore, control of the modulation index is provided without an additional control loop by eliminating the zero state, and thus it could be possible to work with an adjustable DC line voltage. Therefore, voltage stress across the inverter switches is limited. Limited voltage stress provides higher efficiency by reducing switching losses, and it also helps to reduce the cost by allowing the use of low-cost switches. The performance of the proposed ZSI control method is verified through Matlab/Simulink simulations.