Switching Characteristic Analysis and Application Assessment of SiC MOSFET With Common Source Inductance and Kelvin Source Connection

SiC mosfets with packages of common source inductance (TO-247-3) and kelvin source connection (TO-247-4) are both widely used devices in the existing power conversion. Transient analysis of switching characteristics reveals some evaluation mistakes and misguidance design by using the conventional test circuit due to the difference packages. However, the more precise gate characteristic of TO-247-3 SiC mosfet can be obtained by using TO-247-4 device package. Based on the unique feature, this article provides an improved evaluation method to get a comprehensive comparison of TO-247-3 and TO-247-4 SiC mosfet commutation as the active and passive switch devices in the typical half-bridge circuit. The results indicate that 4-PIN SiC mosfet has both advantages of low switching loss and reduced dv/dt. Furthermore, this article first reveals that the widely used drive design for TO-247-3 mosfet with active miller clamped drive IC has a potential irrational circuit defect. Mathematical model analysis and experiment test have been accomplished to verify the superiority of the improved evaluation method. TO-247-4 SiC mosfet is more promising in application of high efficiency, high frequency as well as strict EMI requirement.