United Silicon Carbide, Inc. — Department of Energy SBIR Phase I: 17b

Description

The U.S. represents the worlds leading market for electric vehicles and is producing some of the most advanced plug-in electric vehicles PEVs) available today. PEVs are gaining widespread adoption every year, where 58% of all PEV sales occurred in 2013 and it is expected that by 2023, there will be ~3.2 million PEVs on the road in the U.S. alone. To increase adoption and maintain this leadership, the EV Everywhere initiative has set the goal to make electric vehicles as affordable as gasoline vehicles by 2022. To meet the goals of the EV Everywhere initiative, the primary efforts lie in reducing costs for the batteries, PM motor and electric drive train while simultaneously reducing weight. Increasing the drive train conversion efficiency has a significant impact as it extends battery life, vehicle range and allows for a reduction of heavy cooling components through the reduction of heat generating losses. Therefore much attention is placed on increasing the efficiency of the traction power inverter that drives the electric motor. It is well documented that inverter efficiency and power density can be increased while simultaneously reducing weight through the use of Silicon Carbide SiC) wide bandgap semiconductors. For example, demonstrations of inverters utilizing SiC-JFETs and SiC-MOSFETs are emerging, where the efficiencies are reaching >99% with 10X increased power densities. However, todays electric vehicle motor drive applications require high current 200-400A) power modules. SiC devices have been limited to lower current <50A) due to the material defects, lower yields and higher costs associated with large area devices. For the electric vehicle traction inverters, it is of great interest to push up the SiC device current to 100-200A per device to make full use of the SiC system. Material defect densities have dropped dramatically in recent years as the commercial acceptance of the SiC Schottky diode have driven higher volume and more state-of-the-art semiconductor fabrication. To address topic 17b, USCi proposes in Phase I to fabricate 200A 650V SiC Schottky Diodes on 6 diameter wafers. The high current diodes will begin reliability qualifications in Phase I. The cost of manufacturing SiC diodes will be addressed in Phase I as well. In Phase II, the diodes will be co-packaged with Si switches to form hybrid modules. When integrated, the SiC diodes will increase the efficiency of electric motor power conversion from the battery to the drive train. In Phase II, the goal will be to qualify the high current diodes on the system level for automotive applications.