Small signal modeling of a novel single-phase photovoltaic inverter

The dual mode time-sharing photovoltaic (PV) inverter is generally of higher efficiency compared to other types because only one power stage operates in the high switching frequency state at any time. In this paper, small-signal-model comparison was made between the conventional dual mode time-sharing inverter and the proposed dual mode time-sharing cascaded inverter. It has been revealed with modeling that the control-to-output voltage transfer function of the conventional inverter has right half plane zero, and the system is difficult to be controlled well, additionally, a simple compensator could hardly meet the requirement on system's phase margin and amplitude margin when the input voltage is lower than a half peak value of the output voltage. However, it becomes much easier to design a desired compensator for the proposed buck-type inverter. The experiments in a 1 kW prototype of proposed inverter verified the theoretical analysis.