ST targets Electric Vehicles with SiC power devices
Today’s power modules typically rely on standard silicon diodes and Insulated Gate Bipolar Transistors (IGBTs). Silicon carbide is a newer, wide-bandgap technology that allows smaller device geometries capable of operating well above the 400V range of today’s electric and hybrid drivetrains. The smaller SiC diode and transistor structures present lower internal resistance and respond more quickly than standard silicon devices, which minimize energy losses and allow associated components to be smaller, saving size and weight.
“Major carmakers and automotive Tier-1s are now committing to silicon-carbide technology for future product development to leverage its higher aggregate efficiency compared to standard silicon in a wide range of operating scenarios,” said Mario Aleo, Group Vice President and General Manager, Power Transistor Division, STMicroelectronics. According to Aleo, ST has reached reached an advanced stage of qualification for its SiC devices. The company at the same time specified 2017 as the timeframe to launch new SiC products.
ST has been among the first companies to produce silicon-carbide high-voltage MOSFETs, with its first 1200V SiC MOSFET introduced back in 2014, achieving 200°C rating for more efficient and simplified designs.
Having introduced its first SiC high-voltage MOSFETs back in 2014. the company is using a highly advanced process to fabricate SiC MOSFETs and diodes on 4-inch wafers. In order to drive down the manufacturing costs, improve the quality, and deliver the large volumes demanded by the auto industry, ST is scaling up its production of SiC MOSFETs and diodes to 6-inch wafers, and is on schedule to complete both conversions by the end of 2016.
ST has already qualified its 650V SiC diodes to AEC-Q101, and will complete qualification of the latest 650V SiC MOSFETs and 1200V SiC diodes in early 2017. The qualification of the new-generation 1200V SiC MOSFETs will be completed by the end of 2017. The STPSC20065WY 650V SiC diode is in full production now in DO-247. The range also includes lower current ratings and smaller form-factor TO-220 package options. The STPSC10H12D 1200V SiC diode is sampling now to lead customers in the TO-220AC package and goes to production this month, with volume production of the automotive-grade version planned for Q4 2016. Multiple current ratings from 6A to 20A and packaging options will also be available. The SCTW100N65G2AG 650V SiC MOSFET is sampling now to lead customers in the HiP247 package. It will ramp up in volumes in H1 2017. To enable more compact designs, a 650V SiC MOSFET in the surface-mount H2PAK will also be qualified to AEC-Q101 in H1 2017.
For further information on ST’s portfolio of SiC devices please refer to www.st.com/sicmos for MOSFETs or www.st.com/auto-sic-diodes for diodes.
The sue of a SiC MOSFET in the EV/HEV main inverter, running at typical frequencies up to 20kHz, increases the efficiency compared with an equivalent IGBT solution by up to 3%. This dramatic improvement translates into longer battery life and autonomy, and a smaller and lighter power unit with lower cooling requirements. SiC MOSFET reduce power losses in the inverter by up to 80% lower at light/medium load, enabling designers to use higher switching frequencies for more compact designs. Additionally, a SiC-based solution offers highly robust intrinsic-body diodes, eliminating the need for the freewheeling diodes necessary with IGBTs, further saving cost, size, and weight.
In other EV/HEV applications like the OBC (On-Board Charger) and DC-DC Converter, the inherently faster switching performance of SiC, compared with standard silicon devices, allows much higher switching frequencies, thus reducing the size of passive components. Furthermore, the SiC MOSFET increases design flexibility as it can be used in diverse topologies.
ST’s SiC MOSFETs, housed in a proprietary high-thermal-efficiency HiP247 package, also feature the industry’s highest junction-temperature rating of 200°C and show a very small variation of the on-state resistance even at high temperatures. This leads to higher system efficiency, which reduces cooling requirements and PCB form factors simplifying thermal management.
The new 650V and 1200V SiC diodes from ST have the best-in-class forward voltage drop (VF) among all devices in the market today, which minimizes the amount of energy dissipated as heat by EV/HEV power converters. These excellent thermal properties help to further improve overall vehicle reliability.
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