The Advantage of SiC MOSFET for Three-phase Four Legs Converter in Off-grid Applications

Abstract:
Commercial and industrial (C&I) side energy storage system (ESS) is booming recently with its economy, flexibility, and grid friendliness. In the off-grid application scenario, the unbalanced load capability and output power quality are important indicators of its power conversion system (PCS). The three-phase four legs(3P4L) converter has the strongest ability to supply unbalanced loads but compared to the three-phase three legs (3P3L) topology, the cost increases and the output AC voltage harmonic distortion is higher. SiC MOSFETs can significantly increase the switching frequency compared with IGBTs due to their superior material characteristics. In this paper, the theoretical analysis combined with the simulation results show that SiC MOSFETs are more suitable for 3P4L converter, which is a cost performance solution.