Robust Model-Free Control of Grid-Connected Converters with Fast Dynamic and High Quality Performance

Abstract

A robust combined control method of grid-connected converters is proposed in this paper. The method regulates the grid current vector in a two-phase stationary frame using hysteresis controllers and a novel dynamic switching logic. It is model-free and has a simple control system structure with low online calculations. In addition, the method avoids any pulse-width modulation sub-system and reference frame transformation of either voltage or current. Moreover, fast dynamic power response and low current THD are obtained under the proposed dynamic switching logic. Furthermore, the proposed method is a good choice from the grid protection point of view due to a direct current magnitude regulation. Compared to the vector control method, the proposed control system lacks any grid parameter dependency, PI controller, and PWM-subsystem.