Investigation on the short-circuit behavior of HV-SiC-MOSFETs in quasi series connection

• In many converter topologies, combinations of short-circuit type I with short-circuit type II or III can occur, referred to as short circuits in quasi series connected devices. • These short-circuit cases are experimentally investigated using a 3.3-kV SiC MOSFET half-bridge module. • Measurements show a highly unequal voltage and energy sharing during short-circuit events between the high-side and low-side switch of the module in favor of the low-side switch, independent of the tested scenario. • Spice simulations reveal asymmetric common-source parasitics – especially the resistive component – as the root cause for uneven load distribution. This paper investigates the short-circuit behavior of SiC MOSFETs in a quasi series connection, a scenario that can be found in more complex topologies, but also in simple two-level phase legs. Besides a theoretical analysis, short-circuit tests for such scenarios are carried out with state-of-the-art 3.3-kV SiC MOSFET half-bridge modules. The analysis particularly focuses on the voltage distribution between the switches within a half-bridge module, evaluating the impact of different device parasitics with impact on the gate circuit.