A 1.2 kV 400A SiC-MOSFET Based 3L-TNPC Power Module With Improved Hybrid Packaging Method for High-Density Applications

Three-level T-type neutral-point-clamped converters (3L-TNPC) are widely used in motor drive and PV applications because of the higher efficiency, improved output THD, and lower common-mode noise. But such topology suffers from high stray inductance because of the complicated power loop structure. This paper proposes a SiC-MOSFET based 3L-TNPC power module with a hybrid packaging method. The module has a printed circuit board (PCB) directly soldered on top of direct bounding copper (DBC), with bare dies soldered on DBC and connecting to PCB by bonding wires. Such a structure allows the power loop on both DBC and PCB. This reduces stray inductance through enhanced mutual-inductance cancellation. The introduced PCB can provide extra flexibility in gate-loop optimization, enabling synchronous gate drive between parallel dies. The heat from dies can also be directly dissipated through DBC and the proposed direct-soldered coldplate. A 1.2 kV, 400 A SiC 3L-TNPC module is fabricated with measured loop inductance of 2.5 nH. Faster driving speed by using 0.33Ω gate resistance is enabled to reduce switching loss. Eventually, double-pulse tests and continuous tests are carried out to evaluate the module.