Influence of Device Parameter and Parasitic Inductances on Transient Behaviors of Parallel Connection of SiC GTOs

Silicon Carbide (SiC) gate turn-off thyristor (GTO) is very promising in high power systems such as HVDC and megawatt tractions. And the parallel connection of several single power devices is necessary because the capability of a discrete power device is still very limited. This paper deals with the transient behaviors of parallel connected SiC GTOs. We investigated the influence of device parameters and package and/or layout induced parasitic inductances on the transient behaviors of paralleled SiC GTOs under same gate driver capability by TCAD simulations. The device parameters' variations affect the magnitude of the current peak during turning on, but have little influence on turn-off transient. While the asymmetric parasitic inductances in the electrodes not only affect the current peak during turning on, but also could bring out current commutation in different SiC GTOs during turning off and may cause turn-off failures. A powerful gate driver was also found to be a solution to the mismatched parasitic inductance induced turn-off failure, but it would be more complex and expensive.