SiC MOSFET Based LCL Grid-Connected Inverter with Double Closed-Loop Control

Power inverter is an important part of a grid-connected system, LCL filter is widely used in the grid-connected inverter due to its harmonic attenuation performance and system stability. Compared with the traditional power device IGBT, SiC MOSFET has shown obvious advantages in higher switching frequency as a result of high power density. This paper first analyzes the effect of passive damping method on the resonance peak; then a double closed-loop control strategy with the inner loop of capacitor current and the outer loop of grid current is introduced; finally, the experimental platforms of SiC MOSFET inverter are built. The experimental results show that the double closed-loop control based on the LCL filter three-phase grid-connected inverter significantly reduces the system harmonics, and confirms the feasibility of the control strategy parameters design scheme.