Performance Evaluation of High-Power SiC MOSFET Modules in Comparison to Si IGBT Modules

TLDR

The higher voltage blocking capability and faster switching speed of silicon‑carbide (SiC) MOSFETs make them promising replacements for Si IGBTs in medium‑ to low‑voltage, high‑power applications. The study fully characterizes a 325 A, 1700 V SiC MOSFET module across load currents, bus voltages, and gate resistors to assess its switching performance. The authors compare the SiC MOSFET module to similarly rated Si IGBTs by testing both under identical load currents, bus voltages, and gate resistor settings. The tests show that the SiC MOSFET’s overshoot current scales linearly with load current, its negative‑gate crosstalk is more damaging than positive crosstalk, and its switching losses are substantially lower than those of Si IGBTs even with low gate resistance, while a validated power‑loss model predicts 96.2 % efficiency at 80 kHz for 100 kW operation.

Abstract

The higher voltage blocking capability and faster switching speed of silicon-carbide (SiC) mosfets have the potential to replace Si insulated gate bipolar transistors (IGBTs) in medium-/low-voltage and high-power applications. In this paper, a state-of-the-art commercially available 325 A, 1700 V SiC mosfet module has been fully characterized under various load currents, bus voltages, and gate resistors to reveal their switching capability. Meanwhile, Si IGBT modules with similar power ratings are also tested under the same conditions. From the test results, several interesting points have been obtained: different to the Si IGBT module, the over-shoot current of the SiC mosfet module increases linearly with the increase of the load current and it has been explained by a model of the over-shoot current proposed in this paper; the induced negative gate voltage due to the complementary device turn-off (crosstalk effect) is more harmful to the SiC mosfet module than the induced positive gate voltage during turn-on when the gate off-voltage is -6 V; the maximum dv/dt and di/dt (electromagnetic interference) during switching transients of the SiC mosfet module are close to those of the Si IGBT module when the gate resistance is larger than 8 Ω but the switching loss of the SiC mosfet module is much smaller; the switching losses of the Si IGBT module are greater than those of the SiC mosfet module even when the gate resistance of the former is reduced to zero. An accurate power loss model, which is suitable for a three-phase two-level converter based on SiC mosfet modules considering the power loss of the parasitic capacitance, has been presented and verified in this paper. From the model, a 96.2% efficiency can be achieved at the switching frequency of 80 kHz and the power of 100 kW.