In this work, we report our recently developed 27 kV, 20 A 4H-SiC n-IGBTs. Blocking voltages exceeding 24 kV were achieved by utilizing thick (210 μm and 230 μm), lightly doped N-drift layers with an appropriate edge termination. Prior to the device fabrication, an ambipolar carrier lifetime of greater than 10 μs was measured on both drift regions by the microwave photoconductivity decay (μPCD) technique. The SiC n-IGBTs exhibit an on-state voltage of 11.8 V at a forward current of 20 A and a gate bias of 20 V at 25 °C. The devices have a chip size of 0.81 cm2and an active conducting area of 0.28 cm2. Double-pulse switching measurements carried out at up to 16 kV and 20 A demonstrate the robust operation of the device under hard-switched conditions; coupled thermal analysis indicates that the devices can operate at a forward current of up to 10 A in a hard-switched environment at a frequency of more than 3 kHz and a bus voltage of 14 kV.
The 4H-SiC n-IGBT is a promising power semiconductor device for medium voltage power conversion. Currently, Cree has successfully built 15 kV n-IGBTs. These IGBTs are pivotal for the smart grid power conversion systems and medium voltage drives. The need for complex multi-level topologies or series connected devices can be eliminated, while achieving reduced power loss, by using the SiC IGBT. In this paper, characteristics of the 15 kV n-IGBT have been reported for the first time. The turn-on and turn-off transitions of the 15 kV, 20 A IGBT have been experimentally evaluated up to 11 kV. This is highest switching characterization voltage ever reported on a single power semiconductor device. The paper includes static characteristics up to 25 A (forward) and 12 kV (blocking). The dependency of the power loss with voltage, current and temperature are provided. In addition, the basic converter design considerations using this ultrahigh voltage IGBT for high power conversion applications are presented. Also, a comparative evaluation is reported with an IGBT with thicker field-stop buffer layer as a means to show flexibility in choosing the IGBT design parameters based on the power converter frequency and power rating specification. Finally, power loss comparison of the IGBTs and MOSFET is provided to consummate the results for a complete reference.
Advanced high-voltage (10 kV -15 kV) silicon carbide (SiC) power MOSFETs described in this paper have the potential to significantly impact the system performance, size, weight, high-temperature reliability, and cost of nextgeneration energy conversion and transmission systems. In this paper, we report our recently developed 10 kV/20 A SiC MOSFETs with a chip size of 8.1 × 8.1 mm 2 and a specific onresistance (R ON,SP ) of 100 mΩ⋅cm 2 at 25 °C. We also developed 15 kV/10 A SiC power MOSFETs with a chip size of 8 × 8 mm 2 and a R ON,SP of 204 mΩ⋅cm 2 at 25 °C. To our knowledge, this 15 kV SiC MOSFET is the highest voltage rated unipolar power switch. Compared to the commercial 6.5 kV Silicon (Si) IGBTs, these 10 kV and 15 kV SiC MOSFETs exhibit extremely low switching losses even when they are switched at 2-3x higher voltage. The benefits of using these 10 kV and 15 kV SiC MOSFETs include simplifying from multilevel to twolevel topology and removing the need for time-interleaving by improving the switching frequency from a few hundred Hz for Si based systems to ≥ 10 kHz for hard-switched SiC based systems.
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