Sliding-mode control of a transformer-less dual-stage grid-connected photovoltaic micro-inverter

A transformer-less topology of a grid-connected photovoltaic micro-inverter applying sliding-mode control is discussed in this paper. The proposed structure is a dual-stage topology with a quadratic boost converter in the DC-DC stage and a full-bridge inverter in the DC-AC stage. The quadratic boost uses a multi-loop scheme with a sliding-mode current controller and a proportional-integral (PI) compensator regulating the output voltage. The full-bridge inverter injects real power to the grid by means of a sinusoidal reference sliding-mode tracking-loop whose amplitude is defined by a maximum power point tracker (MPPT). This preliminary work involves an analytical discussion and several simulation results of each converter and of the overall system.