Layout of Series-connected SiC MOSFET Devices for Medium Voltage Applications

A rated 9.6kV, 450A half-bridge module composed of eight series-connected 1.2kV SiC power MOSFETs is constructed. The key layout considerations in terms of the electrical, thermal and insulation issues are specially addressed from the application perspective. At first, the influence of the parasitic parameters and temperature variation on voltage imbalance of the series connected devices is analyzed briefly to guide the design of the layout. Then split heatsink scheme is adopted to enable reliable insulation. Meanwhile a balanced liquid cooling system is designed and verified at 180 square operation. Afterwards the laminated busbar with a 62% stray inductance reduction compared with discrete busbar is proposed. Finally, an optimized layout of the snubber circuit is demonstrated with facilitated voltage balance benefit. The proposed module functions as a single SiC 9.6kV/450A half bridge module and can be adopted in the medium voltage converters flexibly.