Can SiC MOSFETs improve the dynamics of grid-connected voltage source inverters?

Abstract

This work investigates the dynamic behavior of grid-connected voltage source inverters with special focus on the differences that the use of SiC MOSFETs instead of Si IGBTs introduce to the system. SiC MOSFETs allow for a higher control bandwidth due to higher switching frequencies. Therefore, the current reference step response may achieve shorter settling times. However, SiC MOSFET based voltage source inverters may not react faster to grid faults despite the higher achievable current controller bandwidth, because the dynamics of the grid voltage amplitude and angle detection dominate the inverter current transients after grid faults. The reactive current settling time is largest during grid faults with high phase jump and small voltage sag depth. The study is based on mathematical models, time domain simulations and laboratory experiments.