Single-phase grid-connected photovoltaic system based on boost inverter

A grid-connected inverter consisted of two boost converters is proposed for single-phase grid-connected photovoltaic systems. The double loop control structure included outer current loop and inner voltage loop is designed for the system. The phase error between grid-connected current and grid voltage is computed when the negative zero-crossing of grid voltage is detected, and the phase adjustment quantity is computed by PI controller. The amplitude and phase of grid-connected reference current are adjusted when the positive zero-crossing of grid voltage is detected. The error between the reference current and actual current is as the input of the PI controller, and the output added to grid voltage is used as the given voltage for the inner voltage loop. The sliding mode controller is designed for the boost inverter. The proposed methods are simulated, and the results show that the grid-connected current has good sine degree, and is synchronous with grid voltage. The amplitude of reference grid-connected current is tracked with no error.