A Robust Composite Control Method for LCL Grid-connected Inverter Based on SiC MOSFETs under Weak Grid

摘要

The active damping method based on proportional voltage feedforward is usually used to solve the inherent resonance and low-order harmonics of LCL filter. However, in the case of low short-circuit capacity and high impedance of weak grid, the grid impedance has a great influence on the control performance, especially for high-frequency inverters based on SiC MOSFET. In order to improve the stability of the inverter, this paper proposes a robust composite control method, which combines grid-connected current feedback active damping, full voltage feedforward and improved current controller. This method can not only adapt to the wide range of changes in grid impedance, but also suppress background harmonics. The simulation and experimental results verify the effectiveness of the proposed method.