Control of z-source photovoltaic inverter for grid-connected based on constant-frequency hysteresis current control

Abstract

In order to achieve high-efficient grid-connected control of photovoltaic generation system, in this paper the hysteresis current control has been introduced in the z-source inverter for grid-connected control. Combining both of these advantages, the method of z-source inverter for grid-connected control based on constant-frequency hysteresis control is proposed. Due to the particularity of the shoot-through operating state in z-source inverter, the boosting characteristic of shoot-through vector and performance of voltage control are analyzed. According to the logical analysis, the shoot-through vector control is inserted to the hysteresis grid-connected control. This control technology not only preserves the advantages of quick dynamic response, high tracking precision and stability quality but also overcomes the shortcomings of switching loss and difficulties in filter design caused by non-constant switching frequency. The addition of shoot-through vector realized the stable boosting of DC side and made the AC side meet the requirements of grid-connected. The correctness of theory analysis is validated by simulation and experiment results.