DESC0024990

Existing power semiconductor technologies are fostering the adoption of electrification across a wide range of applications, from transportation to power generation. However, silicon-based power modules are suboptimal due to their low power densities and the low switching frequency capability of existing Si insulated-gate bipolar transistors (IGBTs). By replacing Si with Silicon Carbide (SiC) power modules, it is possible to achieve higher switching frequencies (e.g. 10 kHz versus 1 kHz for Si), and higher power densities while achieving greater efficiencies. In this Phase I project, NoMIS will, in collaboration with the National Renewable Energy Laboratory, design, simulate, and prototype a 3.3 kV, 200 A half-bridge SiC power module. Using optimized substrates and die attachment methodologies, the SiC power module will be assembled and tested to confirm simulations. Lastly, a cost analysis to project COGS at small and large scales will be conducted to ensure that pricing targets can and will be met. At the end of Phase II, NoMIS is targeting the production of a fully packaged and ready-to-integrate module for $6.95/Amp ľ half the cost of current commercial-off-the-shelf solutions. At large scales in 150 mm SiC foundries, NoMIS is targeting <$5/Amp to achieve cost competitiveness with Si IGBT power modules while providing greater benefits. Vital to realizing this vision, NoMIS aims to reduce the junction-to-case thermal resistance by as much as 25% by utilizing copper sintering die attachment between NoMIS SiC power device chips and an organic-based multi-layer substrate, without sacrificing partial discharge inception voltage (PDIV) inside the power module. The proposed packaging technology will allow for cheaper, more robust, and more easily manufacturable power modules, facilitating adoption by remaining compatible with industry-standard packaging processes and relying on an in-house supply of SiC power devices. NoMIS Powerĺs Endura 3300-series SiC MOSFETs have longer short-circuit withstand time (>10 µs), high gate oxide reliability, reduced body diode degradation, and area-efficient edge termination without sacrificing SiC MOSFET on-resistance when compared to other vendors. Endura-series SiC power devices owe their ruggedness to proprietary burn-in and screening procedures that ensure proper device binning prior to assembly for a more reliable power module. The technology developed in this project has ramifications in two primary applications that are being targeted by NoMIS and our customers: EV fast chargers and solid-state transformers. EV fast chargers that are directly driven from MV AC grid voltages (e.g. 13.8 kV) have much lower grid charging currents and hence lower energy losses compared to chargers connected from the 480 V AC mains, as conduction losses from cabling can be drastically minimized. Moreover, with the advent of vehicle-to-grid (V2G) technologies, SiC-based technologies are the ideal choice for bidirectional converters at these medium voltages due to the higher efficiencies and higher switching frequencies that SiC enables, bringing with it the additional advantages of smaller passive components and higher power densities. Complementarily, to support such EV fast chargers, the electrical grid itself will need to make use of more robust solid-state transformers to provide sufficient power processing capability while surviving power demand surges and integrating low and high-voltage networks.