Advantages of SiC-Based Devices on the Design of Dual-Active Bridge DC/DC Converter for DC faults

DC short circuit fault ride-through is a critical feature for the reliability and performance of DC microgrids. This paper presents the advantage that SiC-based devices offer for designing a Dual-Active Bridge (DAB) DC-DC converter while considering DC short circuit events. It is known that SiC-MOSFET devices have a higher transient current carrying capability than Si-IGBT devices due to their superior thermal conductivity. This characteristic of SiC-MOSFET devices is utilized to improve the design of DAB for DC short circuit fault ride-through applications. An analytical model is developed to understand the performance of a DAB during DC short circuit faults. Switching and thermal simulations are used to validate the analytical model and compare DAB designs based on SiC-MOSFET and Si-IGBT. The advantages of SiC-MOSFET enabled DAB compared to Si-IGBT enabled DAB are also quantified for a particular application of DAB in a DC microgrid. It is shown that for fault ride-through applications, DAB enabled with SiC-MOSFET can be designed for lower phase shifts compared to Si-IGBT enabled DAB, which inherently reduces the inductor size and circulating current in a DAB.