SiC MOSFET Module Replaces up to 3x Higher Current Si IGBT Modules in Voltage Source Inverter Application

February 2013 www.bodospower.com INTRODUCTION SiC is currently the only wide bandgap material to address the power electronics market needs for high performance 1200V and 1700V devices. SiC diode technology has thrived in the market for more than a decade, and many switches have recently become available to enable “all-SiC” circuit solutions. For example, in November 2012, Cree announced the industry’s first fully qualified, fully documented all-SiC module (CAS100H12AM1 1200V, 100A SiC MOSFET module) ready for immediate evaluation/design activity and high volume manufacturing as seen in Figure 1. The 50mm x 90mm x 25mm halfbridge module contains a commercially released chipset including: five 1200V, 80mΩ 1st Generation SiC MOSFETs (CPMF-1200S080B) and five 1200V, 10A 2nd Generation SiC Schottky diodes (CPW2-1200-S010B) per switch. The all-SiC module is assembled with an AlSiC baseplate for better matching of thermal expansion and lighter weight as compared to conventional copper baseplates. The power semiconductors are isolated from the baseplate with a Si3N4 insulator featuring active metal brazed copper joints capable of extended thermal and power cycling. These module properties provide a maximum reliability package for the high performance SiC chips. VSI DESIGN Because of significantly reduced switching loss of SiC devices, a SiC MOSFET of 100 rated Amperes is expected to replace a Si IGBT of much higher rated current. To illustrate and quantify this point, a basic three-phase Voltage Source Inverter (VSI) found in many DC/AC applications such as motor drives, uninterruptable power supplies and solar inverters is defined with the key characteristics as shown in Table 1.