Derivation of a global model of a two-stage photovoltaic microinverter using sliding-mode control

This paper develops a global model of a two-stage grid-connected microinverter which uses sliding-mode control laws in both stages. In the study, it is considered that the microinverter is fed by a current source representing the photovoltaic module with a capacitor connected in parallel. The model of the DC-DC stage is obtained from the linearization of the ideal sliding dynamics of the converter considering that it is controlled through the input current. The DC-AC stage tied to the grid is considered as the load of the DC-DC stage. This representation allows including the voltage regulation loop used to stabilize the DC-link voltage through the value of the output current. The model is used to evaluate the local stability of the DC-link of the microinverter which represents the power balance of the system. The results are validated by means of simulations and experimental results.