Improved Off-time Discrete Control for DCM Grid-tied Inverter with Accurate Average Current Model and Considering Nonlinear Parasitic Capacitance

This paper presents an improved off-time discrete control for discontinuous current mode (DCM) grid-tied inverters to mitigate the deviations between the output current and its reference value. The detailed inductor current behavior is studied and an accurate current model is proposed. The nonlinear characteristics of device parasitic capacitance is considered for the modulation. An advanced off-time discrete control with the improved current model and the compensation for the nonlinear parasitic capacitance is considered for the modulation. The effectiveness of the proposed method was verified by experiments with a fabricated converter, which consists of GaN-HEMT devices and was operated at 1 MHz.